Method of assembling a bone anchor receiver assembly having an insert with rotation blocking extensions and a downward facing collet

ABSTRACT

A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in an integral receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. A friction fit compression insert (some with lock and release feature), a planar split retaining ring and a shank upper portion cooperate to provide for pop- or snap-on assembly of the shank with the receiver either prior to or after implantation of the shank into a vertebra. The shank and receiver once assembled cannot be disassembled and the receiver and insert may include aligned tool receiving apertures for lock and release of the polyaxial mechanism.

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/460,267 filed Dec. 29, 2010 and U.S. ProvisionalPatent Application Ser. No. 61/463,037 filed Feb. 11, 2011, both ofwhich are incorporated by reference herein. This applications is also acontinuation-in-part of U.S. patent application Ser. No. 13/373,289filed Nov. 9, 2011 that claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/456,649 filed Nov. 10, 2010 and U.S. ProvisionalPatent Application Ser. No. 61/460,234 filed Dec. 29, 2010, all of whichare incorporated by reference herein. This application is also acontinuation-in-part of U.S. patent application Ser. No. 12/924,802filed Oct. 5, 2010 that claims the benefit of the following U.S.Provisional Patent Application Ser. No. 61/278,240, filed Oct. 5, 2009;61/336,911, filed Jan. 28, 2010; 61/343,737 filed May 3, 2010;61/395,564 filed May 14, 2010; 61/395,752 filed May 17, 2010; 61/396,390filed May 26, 2010; 61/398,807 filed Jul. 1, 2010; 61/400,504 filed Jul.28, 2010; 61/402,959 filed Sep. 8, 2010; 61/403,696 filed Sep. 20, 2010;and 61/403,915 filed Sep. 23, 2010, all of which are incorporated byreference herein. This application is also a continuation-in-part ofU.S. patent application Ser. No. 12/802,849 filed Jun. 15, 2010 thatclaims the benefit of U.S. Provisional Patent Application Ser. No.61/268,708 filed Jun. 15, 2009, both of which are incorporated byreference herein.

BACKGROUND OF THE INVENTION

The present invention is directed to polyaxial bone screw shanks withheads for use in bone surgery, more specifically to spinal surgery andparticularly to such screws with receiver member assemblies includingcompression or pressure inserts and expansion-only split retainers tosnap over, capture and retain the bone screw shank head in the receivermember assembly and later fix the bone screw shank with respect to thereceiver assembly.

Bone screws are utilized in many types of spinal Surgery in order tosecure various implants to vertebrae along the spinal column for thepurpose of stabilizing and/or adjusting spinal alignment. Although bothclosed-ended and open-ended bone screws are known, open-ended screws areparticularly well suited for connections to rods and connector arms,because such rods or arms do not need to be passed through a closedbore, but rather can be laid or urged into an open channel within areceiver or head of such a screw. Generally, the screws must be insertedinto the bone as an integral unit along with the head, or as apreassembled unit in the form of a shank and pivotal receiver, such as apolyaxial bone screw assembly.

Typical open-ended bone screws include a threaded shank with a pair ofparallel projecting branches or arms which form a yoke with a U-shapedslot or channel to receive a rod. Hooks and other types of connectors,as are used in spinal fixation techniques, may also include similar openends for receiving rods or portions of other fixation and stabilizationstructure.

A common approach for providing vertebral column support is to implantbone screws into certain bones which then in turn support a longitudinalstructure such as a rod, or are supported by such a rod. Bone screws ofthis type may have a fixed head or receiver relative to a shank thereof,or may be of a polyaxial screw nature. In the fixed bone screws, the rodreceiver head cannot be moved relative to the shank and the rod must befavorably positioned in order for it to be placed within the receiverhead. This is sometimes very difficult or impossible to do. Therefore,polyaxial bone screws are commonly preferred. Open-ended polyaxial bonescrews typically allow for a loose or floppy rotation of the head orreceiver about the shank until a desired rotational position of thereceiver is achieved by fixing such position relative to the shankduring a final stage of a medical procedure when a rod or otherlongitudinal connecting member is inserted into the receiver, followedby a locking screw or other closure. This floppy feature can be, in somecases, undesirable and make the procedure more difficult. Also, it isoften desirable to insert the bone screw shank separate from thereceiver or head due to its bulk which can get in the way of what thesurgeon needs to do. Such screws that allow for this capability aresometimes referred to as modular polyaxial screws.

With specific reference to modular snap-on or pop-on polyaxial pediclescrew systems having shank receiver assemblies, the prior art has shownand taught the concept of the receiver and certain retainer partsforming an assembly wherein a contractile locking engagement between theparts is created to fix the shank head with respect to the receiver andretainer. The receiver and shank head retainer assemblies in the priorart have included a contractile retainer ring and/or a lower pressureinsert with an expansion and contraction collet-type of structure havingcontractile locking engagement for the shank head due to direct contactbetween the retainer and/or the collet structure with the receiverresulting in contraction of the retainer ring and/or the collet-typestructure of the insert against the shank head.

The prior art for modular polyaxial screw assemblies has also shown andtaught that the contact surfaces on the outside of the collect and/orretainer and the inside of the receiver can be tapered, conical,radiused, spherical, curvate, multi-curvate, rounded, as well as otherconfigurations to create a contractile type of locking engagement forthe shank head with respect to the receiver.

In addition, the prior art for modular polyaxial screw assemblies hasshown and taught that the shank head can both enter and escape from acollet-like structure on the insert or from the retainer when the insertor retainer is in the up position and within an expansion recess orchamber of the receiver. This is the case unless the insert and/or theretainer are blocked from being able to be pushed back up into receiverbore or cavity.

SUMMARY OF THE INVENTION

The present invention differentiates from the prior art by not allowingthe receiver to be removed from the shank head once the parts aresnapped-on and connected. This is true even if the retainer can go backup into the expansion chamber. This approach or design has been found tobe more secure and to provide more resistance to pull-out forcescompared to the prior art for modular polyaxial screw designs.Collect-like structures extending downwardly from lower pressureinserts, when used in modular polyaxial screw designs, as shown in theprior art, have been found to be somewhat weak with respect to pull-outforces encountered during some spinal reduction procedures. The presentinvention is designed to solve these problems.

The present invention also differentiates from all of the prior art byproviding a split retainer ring and a cooperating insert with acollet-like lower super structure portion, wherein the super structuredoes not participate at all in the locking engagement for the shank headwith respect to the receiver. The expansion-only split or open retainerring in the present invention is positioned entirely below the shankhead hemisphere in the receiver and can be a stronger, more substantialstructure to resist larger pull out forces on the assembly. The retainerring base can also be better supported on a generally horizontal loadingsurface near the lower opening in the bottom of the receiver. Thisdesign has been found to be stronger and more secure when compared tothat of the prior art which uses some type of contractile lockingengagement between the parts, as described above; and, again, onceassembled it cannot be disassembled.

Thus, a polyaxial bone screw assembly according to the inventionincludes a shank having an integral upper portion or head and a body forfixation to a bone; a separate receiver defining an upper open channel,a central bore, a lower cavity and a lower opening; one of (a) a topdrop and rotate friction fit lower compression insert having superstructure providing temporary friction fit with the shank head and (b) atop drop, non-rotatable friction fit insert having a seating surfaceextending between front and rear faces of arms of the receiver and superstructure providing temporary friction fit with the shank head; and aresilient expansion-only split retainer for capturing the shank head inthe receiver lower cavity, the shank head being frictionally engagedwith, but still movable in a non-floppy manner with respect to thefriction fit insert and the receiver prior to locking of the shank intoa desired configuration. In some embodiments the insert completelyextends between receiver arms that define the receiver channel and thusremains aligned with and cannot rotate with respect to the receiver atany stage of assembly. In other embodiments, the top drop and rotateinsert is fixed with respect to the receiver by pressing or crimpingportions of the receiver against the insert. The insert operativelyengages the shank head and is spaced from the retainer by the shank headthat is snapped into insert super structure illustrated as resilientpanels. The shank is finally locked into a fixed position relative tothe receiver by frictional engagement between a portion of the insertlocated above the super structure and the split retainer, as describedpreviously, due to a downward force placed on the compression insert bya closure top pressing on a rod, or other longitudinal connectingmember, captured within the receiver bore and channel. In theillustrated embodiments, retainers and inserts are downloaded into thereceiver, but uploaded retainer embodiments are also foreseen. The shankhead can be positioned into the receiver lower cavity at the loweropening thereof prior to or after insertion of the shank into bone. Somecompression inserts include a lock and release feature for independentlocking of the polyaxial mechanism so the screw can be used like a fixedmonoaxial screw. The shank can be cannulated for minimally invasivesurgery applications. The receiver is devoid of any type of spring tabsor collet-like structures. The pressure insert and/or the retainer areboth devoid of any type of receiver-retainer contractile lockingengagements with respect to the shank head. In some embodiments, theinsert can also have resilient outwardly and upwardly extending armswhich are deployed into openings in the receiver cavity so that theretainer and captured shank head are stabilized and retained in theregion of the receiver locking chamber once they enter into such lowerportion of the receiver cavity. In this way, the shank head and retainercannot go back up into the receiver cavity.

Again, a pre-assembled receiver, friction fit compression insert andsplit retainer may be “pushed-on”, “snapped-on” or “popped-on” to theshank head prior to or after implantation of the shank into a vertebra.Such a “snapping on” procedure includes the steps of uploading the shankhead into the receiver lower opening, the shank head pressing againstthe base of the split retainer ring and expanding the resilient retainerout into an expansion portion or chamber of the receiver cavity followedby an elastic return of the retainer back to an original or near nominalshape thereof after the hemisphere of the shank head or upper portionpasses through the ring-like retainer. The shank head also enters intothe friction fit lower portion of the insert, the panels of the frictionfit portion of the insert snapping onto the shank head as the retainerreturns to a neutral or close to neutral orientation, providing anon-floppy connection between the insert and the shank head. Thefriction fit between the shank head and the insert is temporary and notpart of the final locking mechanism. In the illustrated embodiment, whenthe shank is ultimately locked between the compression insert and thelower portion of the retainer, the friction fit collet-like panels ofthe insert are no longer in a tight friction fit engagement with theshank head and they are not in contact with the receiver. The finalfixation occurs as a result of a locking expansion-type of contactbetween the shank head and the split retainer and an expansion-type ofnon-tapered locking engagement between the retainer ring and the lockingchamber in the lower portion of the receiver cavity. The retainer canexpand more in the upper portion or expansion chamber of the receivercavity to allow the shank head to pass through, but has restrictedexpansion to retain the shank head when the retainer is against thelocking chamber surfaces in the lower portion of the receiver cavity andthe shank head is forced down against the retainer ring during finallocking. In some embodiments, when the polyaxial mechanism is locked,portions of the insert are forced or wedged against opposing surfaces ofthe receiver resulting in an interference, non-contractile lockingengagement, allowing for adjustment or removal of the rod or otherconnecting member without loss of a desired angular relationship betweenthe shank and the receiver. This independent, non-contractile lockingfeature allows the polyaxial screw to function like a fixed monoaxialscrew.

The lower pressure insert may also be configured to be independentlylocked by a tool or instrument, thereby allowing the pop-on polyaxialscrew to be distracted, compressed and/or rotated along and around therod to provide for improved spinal correction techniques. Such a toolengages the pop-on receiver from the sides and then engages the insertto force the insert down into a locked position within the receiver.With the tool still in place and the correction maintained, the rod isthen locked within the receiver channel by a closure top followed byremoval of the tool. This process may involve multiple screws all beingmanipulated simultaneously with multiple tools to achieve the desiredcorrection.

Objects of the invention further include providing apparatus and methodsthat are easy to use and especially adapted for the intended use thereofand wherein the tools are comparatively inexpensive to produce. Otherobjects and advantages of this invention will become apparent from thefollowing description taken in conjunction with the accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of this invention.

The drawings constitute a part of this specification and includeexemplary embodiments of the present invention and illustrate variousobjects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded front elevational view of a polyaxial bone screwassembly according to the present invention including a shank, areceiver, an open expansion-only retainer and a friction fit lowercompression insert, further shown with a portion of a longitudinalconnecting member in the form of a rod and a closure top.

FIG. 2 is an enlarged top plan view of the shank of FIG. 1.

FIG. 3 is reduced cross-sectional view taken along the line 3-3 of FIG.2.

FIG. 4 is an enlarged side elevational view of the receiver of FIG. 1.

FIG. 5 is an enlarged perspective view of the receiver of FIG. 4.

FIG. 6 is an enlarged top plan view of the receiver of FIG. 4.

FIG. 7 is an enlarged bottom plan view of the receiver of FIG. 4.

FIG. 8 is an enlarged cross-sectional view taken along the line 8-8 ofFIG. 6.

FIG. 9 is an enlarged cross-sectional view taken along the line 9-9 ofFIG. 6.

FIG. 10 is an enlarged perspective view of the retainer of FIG. 1.

FIG. 11 is a reduced top plan view of the retainer of FIG. 10.

FIG. 12 is a bottom plan view of the retainer of FIG. 10.

FIG. 13 is an enlarged cross-sectional view taken along the line 13-13of FIG. 11.

FIG. 14 is an enlarged perspective view of the insert of FIG. 1.

FIG. 15 is another enlarged perspective view of the insert of FIG. 1.

FIG. 16 is a front elevational view of the insert of FIG. 14.

FIG. 17 is a reduced top plan view of the insert of FIG. 14.

FIG. 18 is a bottom plan view of the insert of FIG. 14.

FIG. 19 is an enlarged cross-sectional view taken along the line 19-19of FIG. 17.

FIG. 20 is an enlarged cross-sectional view taken along the line 20-20of FIG. 17.

FIG. 21 is an enlarged front elevational view of the retainer andreceiver of FIG. 1 with portions of the receiver broken away to show thedetail thereof, the retainer being shown downloaded into the receiver(in phantom) to an inserted stage of assembly.

FIG. 22 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 21, showing theinsert of FIG. 1, also in front elevational view, in an initial stage ofassembly.

FIG. 23 is an enlarged front elevational view of the retainer, receiverand insert with portions broken away, similar to what is shown in FIG.22, showing the insert in a subsequent stage of assembly, resilient armsof the insert pressing against inner surfaces of the receiver.

FIG. 24 is a reduced front elevational view with portions broken away,similar to FIG. 23, and further showing an enlarged and partial shank ofFIG. 1 in a first stage of assembly with the retainer, a hemisphere ofthe shank head and a vertebra portion both being shown in phantom.

FIG. 25 is a partial front elevational view with portions broken away,similar to FIG. 24, showing the retainer in an expanded state about amid-portion of the shank head, the head hemisphere shown in phantom.

FIG. 26 is a partial front elevational view with portions broken away,similar to FIG. 25, the shank upper portion or head fully captured bythe retainer.

FIG. 27 is another partial front elevational view with portions brokenaway, similar to FIG. 26, the shank upper portion or head being infrictional engagement with lower panels of the insert.

FIG. 28 is an enlarged and partial cross-sectional view taken along theline 28-28 of FIG. 27.

FIG. 29 is a partial front elevational view with portions broken away,similar to FIG. 27, the shank upper portion and retainer being shownpulled down into a seated position within the lower receiver cavity, theinsert arms in a substantially neutral state, capturing the insert belowa ledge of the receiver.

FIG. 30 is a partial front elevational view with portions broken away ofall of the components shown in FIG. 1, the assembly as in FIG. 29 beingshown in a stage of assembly with the rod and closure top.

FIG. 31 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 30, shown in a final locking position.

FIG. 32 is another enlarged and partial front elevational view withportions broken away, similar to FIG. 31.

FIG. 33 is an enlarged cross-sectional view taken along the line 33-33of FIG. 31.

FIG. 34 is an enlarged perspective view of an alternative locking insertfor use with the assembly of FIG. 1 in lieu of the insert shown in FIG.1.

FIG. 35 is a top plan view of the insert of FIG. 34.

FIG. 36 is a front elevational view of the insert of FIG. 34.

FIG. 37 is an enlarged front elevational view with portions broken awayof the receiver and retainer of FIG. 1 and the insert of FIG. 34 inreduced front elevation, the insert shown captured within the receiverand in an un-locked shipping position.

FIG. 38 is a partial front elevational view of the shank, receiver,retainer, rod and closure of FIG. 1, with portions broken away andassembled with the locking insert as shown in FIG. 37, but in a lockedstage of assembly.

FIG. 39 is an enlarged and partial front elevational view, similar toFIG. 38, illustrating the interference locking of the insert against thereceiver.

FIG. 40 is an enlarged and partial cross-sectional view taken along theline 40-40 of FIG. 38.

FIG. 41 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 39, showing the shank, retainer, insert andreceiver remaining in a locked position after removal of the rod andclosure top of FIG. 1 and further showing, in exploded view, analternative deformable rod and cooperating alternative closure top.

FIG. 42 is a partial front elevational view with portions broken away,similar to FIG. 41, showing the alternative rod and closure top fixed tothe remainder of the assembly.

FIG. 43 is a reduced and partial front elevational view with portionsbroken away of the assembly of FIG. 42 without the alternative rod andclosure top, and further showing unlocking of the insert from thereceiver with a two-piece tool having an inner insert engaging portionand an outer tubular holding portion.

FIG. 44 is a reduced and partial front elevational view of the two-piecetool of FIG. 43, holding prongs of the inner insert engaging portionbeing shown in phantom.

FIG. 45 is an enlarged and partial perspective view of the inner insertengaging portion of the tool shown in FIG. 44 with portions broken awayto show the detail thereof.

FIG. 46 is an enlarged and partial perspective view of the assembly ofFIG. 30, but shown with the shank being at an angle with respect to thereceiver and further showing an alternative locking tool forindependently locking the shank with respect to the receiver when theclosure top and rod are in a loose, unlocked relationship with thereceiver as shown.

FIG. 47 is a partial perspective view of a portion of the locking toolof FIG. 46.

FIG. 48 is an enlarged and partial front elevational view of theassembly and locking tool of FIG. 46 with portions broken away to showthe detail thereof.

FIG. 49 is an exploded perspective view of another embodiment of apolyaxial bone screw assembly according to the present inventionincluding a shank, a receiver, a retainer in the form of an open ringand a friction fit crown compression insert, further shown with aportion of a longitudinal connecting member in the form of a rod and aclosure top.

FIG. 50 is an enlarged top plan view of the shank of FIG. 49.

FIG. 51 is reduced cross-sectional view taken along the line 51-51 ofFIG. 50.

FIG. 52 is an enlarged perspective view of the receiver of FIG. 49.

FIG. 53 is a side elevational view of the receiver of FIG. 52.

FIG. 54 is a top plan view of the receiver of FIG. 52.

FIG. 55 is a bottom plan view of the receiver of FIG. 52.

FIG. 56 is an enlarged cross-sectional view taken along the line 56-56of FIG. 54.

FIG. 57 is an enlarged cross-sectional view taken along the line 57-57of FIG. 54.

FIG. 58 is an enlarged perspective view of the retainer of FIG. 49.

FIG. 59 is a front elevational view of the retainer of FIG. 58.

FIG. 60 is a top plan view of the retainer of FIG. 58.

FIG. 61 is a bottom plan view of the retainer of FIG. 58.

FIG. 62 is an enlarged cross-sectional view taken along the line 62-62of FIG. 60.

FIG. 63 is an enlarged perspective view of the insert of FIG. 49.

FIG. 64 is a front elevational view of the insert of FIG. 63.

FIG. 65 is another perspective view of the insert of FIG. 63.

FIG. 66 is a side elevational view of the insert of FIG. 63.

FIG. 67 is a top plan view of the insert of FIG. 63.

FIG. 68 is a bottom plan view of the insert of FIG. 63.

FIG. 69 is an enlarged cross-sectional view taken along the line 69-69of FIG. 67.

FIG. 70 is an enlarged cross-sectional view taken along the line 70-70of FIG. 67.

FIG. 71 is an enlarged front elevational view of the retainer andreceiver of FIG. 49 with portions of the receiver broken away to showthe detail thereof and intermediate positions of the retainer whilebeing downloaded into the receiver being shown in phantom.

FIG. 72 is a front elevational view with portions broken away, similarto FIG. 71, further showing the insert of FIG. 49 in enlarged sideelevation, with an early stage of assembly of the insert being shown inphantom.

FIG. 73 is a front elevational view with portions broken away, similarto FIG. 72, showing the insert rotated within the receiver during anassembly stage subsequent to that shown in FIG. 72.

FIG. 74 is an enlarged perspective view with portions broken away of theassembly shown in FIG. 73 and further showing a subsequent step ofcrimping a portion of the receiver against the insert.

FIG. 75 is an enlarged side elevational view of the assembly shown inFIG. 74.

FIG. 76 is a reduced front elevational view with portions broken away,similar to FIG. 73 and with the crimping of FIGS. 74 and 75 and furthershowing an alternative assembly stage with the shank of FIG. 49 shown inpartial front elevation in which the shank is first implanted in avertebra, shown in phantom, followed by assembly with the receiver,retainer and insert.

FIG. 77 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 76 showing the shank (not implanted in avertebra) in a stage of assembly with the retainer, the retainer beingpushed up into engagement with the insert.

FIG. 78 is an enlarged partial front elevational view with portionsbroken away, similar to FIG. 77, showing the retainer in an expandedstate about an upper portion of the shank, the shank upper portion in astage of assembly with the insert.

FIG. 79 is a reduced partial front elevational view of the assembly asshown in FIG. 78, with further portions broken away to show the stage ofassembly between the shank upper portion, the retainer and the insert.

FIG. 80 is a reduced partial front elevational view with portions brokenaway, similar to FIG. 78, the shank upper portion in frictionalengagement with the insert and the retainer in a substantially neutralstate.

FIG. 81 is an enlarged partial front elevational view of the assembly asshown in FIG. 80, with further portions broken away to show theengagement between the shank upper portion and the insert.

FIG. 82 is a reduced partial front elevational view with portions brokenaway, similar to FIGS. 80 and 81, showing the assembly in a lockedposition with the rod and closure top of FIG. 49, also shown in frontelevation with portions broken away.

FIG. 83 is a reduced and partial side elevational view of the assemblyof FIG. 82.

FIG. 84 is an enlarged perspective view of an alternative locking insertaccording to the invention for use in the assembly of FIG. 49 in lieu ofthe insert shown in FIG. 49.

FIG. 85 is an enlarged side elevational view of the insert of FIG. 84with portions broken away to show the detail thereof.

FIG. 86 is an enlarged front elevational view of the insert of FIG. 84with portions broken away to show the detail thereof.

FIG. 87 is an enlarged front elevational view of the receiver andretainer of FIG. 49 shown assembled with the insert of FIG. 84, also infront elevation, with portions broken away to show the detail thereof.

FIG. 88 is a reduced side elevational view of the assembly of FIG. 87.

FIG. 89 is a reduced front elevational view of the receiver (withportions broken away), retainer and insert of FIG. 87 further shownassembled with a shank of FIG. 49, shown in partial front elevation, andin a stage of assembly with the rod and closure top of FIG. 49, alsoshown in front elevation.

FIG. 90 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 89 but showing the insert in lockedassembly with the receiver, retainer, rod and closure top.

FIG. 91 is a reduced partial front elevational view with portions brokenaway, similar to FIG. 90, but shown with the rod and closure topremoved, the locking insert remaining in locked relation with respect tothe receiver, and further being shown with an alternative deformable rodand cooperating closure top, shown in exploded view.

FIG. 92 is a partial front elevational view with portions broken away,similar to FIG. 91 showing the alternative deformable rod and closuretop in locked relationship with the rest of the assembly.

FIG. 93 is a reduced and partial front elevational view with portionsbroken away of the assembly of FIG. 91 without the alternative rod andclosure top, and further showing unlocking of the insert from thereceiver with a two-piece tool having an inner insert engaging portionand an outer tubular holding portion.

FIG. 94 is a reduced and partial front elevational view of the two-piecetool of FIG. 93, holding prongs of the inner insert engaging portionbeing shown in phantom.

FIG. 95 is an enlarged and partial perspective view of the inner insertengaging portion of the tool shown in FIG. 94 with portions broken awayto show the detail thereof.

FIG. 96 is an enlarged and partial perspective view of an assemblyidentical to that shown in FIG. 90 with the exception of the shank beingat an angle with respect to the receiver and further showing analternative locking tool for independently locking the shank withrespect to the receiver when the closure top and rod are in a loose,unlocked relationship with the receiver.

FIG. 97 is a partial perspective view of a portion of the locking toolof FIG. 96.

FIG. 98 is an enlarged and partial front elevational view of theassembly and locking tool of FIG. 96 with portions broken away to showthe detail thereof.

DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention, which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure. It is also noted that any reference tothe words top, bottom, up and down, and the like, in this applicationrefers to the alignment shown in the various drawings, as well as thenormal connotations applied to such devices, and is not intended torestrict positioning of the bone attachment structures in actual use.

With reference to FIGS. 1-33 the reference number 1 generally representsa polyaxial bone screw apparatus or assembly according to the presentinvention. The assembly 1 includes a shank 4, that further includes abody 6 integral with an upwardly extending upper portion or headstructure 8; a receiver 10; an open ring retainer 12, and a compressionor pressure insert 14 having structure for friction fit non-lockingengagement with the shank head 8. The receiver 10, retainer 12 andcompression insert 14 are initially assembled and may be furtherassembled with the shank 4 either prior or subsequent to implantation ofthe shank body 6 into a vertebra 17 (see FIG. 24), as will be describedin greater detail below. FIGS. 1 and 31-33 further show a closurestructure 18 for capturing a longitudinal connecting member, forexample, a rod 21 which in turn engages the compression insert 14 thatpresses against the shank upper portion 8 into fixed frictional contactwith the retainer 12, so as to capture, and fix the longitudinalconnecting member 21 within the receiver 10 and thus fix the member 21relative to the vertebra 17. The illustrated rod 21 is hard, stiff,non-elastic and cylindrical, having an outer cylindrical surface 22. Itis foreseen that in other embodiments, the rod 21 may be elastic,deformable and/or of different materials and cross-sectional geometries.The receiver 10 and the shank 4 cooperate in such a manner that thereceiver 10 and the shank 4 can be secured at any of a plurality ofangles, articulations or rotational alignments relative to one anotherand within a selected range of angles both from side to side and fromfront to rear, to enable flexible or articulated engagement of thereceiver 10 with the shank 4 until both are locked or fixed relative toeach other near the end of an implantation procedure.

The shank 4, best illustrated in FIGS. 1-3, is elongate, with the shankbody 6 having a helically wound bone implantable thread 24 (single ordual lead thread form and different thread types) extending from near aneck 26 located adjacent to the upper portion or head 8, to a tip 28 ofthe body 6 and extending radially outwardly therefrom. During use, thebody 6 utilizing the thread 24 for gripping and advancement is implantedinto the vertebra 17 leading with the tip 28 and driven down into thevertebra with an installation or driving tool (not shown), so as to beimplanted in the vertebra to a location at or near the neck 26, as morefully described in the paragraphs below. The shank 4 has an elongateaxis of rotation generally identified by the reference letter A.

The neck 26 extends axially upward from the shank body 6. The neck 26may be of the same or is typically of a slightly reduced radius ascompared to an adjacent upper end or top 32 of the body 6 where thethread 24 terminates. Further extending axially and outwardly from theneck 26 is the shank upper portion or head 8 that provides a connectiveor capture apparatus disposed at a distance from the upper end 32 andthus at a distance from the vertebra 17 when the body 6 is implanted insuch vertebra.

The shank upper portion 8 is configured for a pivotable connectionbetween the shank 4 and the retainer 12 and receiver 10 prior to fixingof the shank 4 in a desired position with respect to the receiver 10.The shank upper portion 8 has an outer, convex and substantiallyspherical surface 34 that extends outwardly and upwardly from the neck26 that in some embodiments terminates at a substantially planar top orrim surface 38. In the illustrated embodiment, a frusto-conical surface39 extends from the spherical surface 34 to the top surface 38,providing additional clearance during pivoting of the shank with respectto the receiver 10 and the insert 14. The spherical surface 34 has anouter radius configured for temporary frictional, non-floppy, slidingcooperation with panels of the insert 14 having concave or flatsurfaces, as well as ultimate frictional engagement with the insert 14at upper inner stepped surface thereof, as will be discussed more fullyin the paragraphs below. The shank top surface 38 is substantiallyperpendicular to the axis A. The spherical surface 34 shown in thepresent embodiment is substantially smooth, but in some embodiments mayinclude a roughening or other surface treatment and is sized and shapedfor cooperation and ultimate frictional engagement with the compressioninsert 14 as well as ultimate frictional engagement with the retainer12. The shank spherical surface 34 is locked into place exclusively bythe insert 14 and the retainer 12 and not by inner surfaces defining thereceiver cavity.

A counter sunk substantially planar base or stepped seating surface 45partially defines an internal drive feature or imprint 46. Theillustrated internal drive feature 46 is an aperture formed in the topsurface 38 and has a star shape designed to receive a tool (not shown)of an Allen wrench type, into the aperture for rotating and driving thebone screw shank 4. It is foreseen that such an internal tool engagementstructure may take a variety of tool-engaging forms and may include oneor more apertures of various shapes, such as a pair of spaced apartapertures or a multi-lobular or hex-shaped aperture. The seat or basesurfaces 45 of the drive feature 46 are disposed substantiallyperpendicular to the axis A with the drive feature 46 otherwise beingcoaxial with the axis A. As illustrated in FIGS. 2 and 3, the drive seat45 may include beveled or stepped surfaces that may further enhancegripping with the driving tool. In operation, a driving tool (not shown)is received in the internal drive feature 46, being seated at the base45 and engaging the faces of the drive feature 46 for both driving androtating the shank body 6 into the vertebra 17, either before the shank4 is attached to the receiver 10 as shown, for example, in FIG. 24, orafter the shank 4 is attached to the receiver 10, with the shank body 6being driven into the vertebra 17 with the driving tool extending intothe receiver 10.

The shank 4 shown in the drawings is cannulated, having a small centralbore 50 extending an entire length of the shank 4 along the axis A. Thebore 50 is defined by an inner cylindrical wall of the shank 4 and has acircular opening at the shank tip 28 and an upper opening communicatingwith the external drive 46 at the driving seat 45. The bore 50 iscoaxial with the threaded body 6 and the upper portion 8. The bore 50provides a passage through the shank 4 interior for a length of wire(not shown) inserted into the vertebra 17 prior to the insertion of theshank body 6, the wire providing a guide for insertion of the shank body6 into the vertebra 17. It is foreseen that the shank could be solid andmade of different materials, including metal and non-metals.

To provide a biologically active interface with the bone, the threadedshank body 6 may be coated, perforated, made porous or otherwisetreated. The treatment may include, but is not limited to a plasma spraycoating or other type of coating of a metal or, for example, a calciumphosphate; or a roughening, perforation or indentation in the shanksurface, such as by sputtering, sand blasting or acid etching, thatallows for bony ingrowth or ongrowth. Certain metal coatings act as ascaffold for bone ingrowth. Bio-ceramic calcium phosphate coatingsinclude, but are not limited to: alpha-tri-calcium phosphate andbeta-tri-calcium phosphate (Ca₃(PO₄)₂, tetra-calcium phosphate(Ca₄P₂O₉), amorphous calcium phosphate and hydroxyapatite(Ca_(n)(PO₄)₆(OH)₂). Coating with hydroxyapatite, for example, isdesirable as hydroxyapatite is chemically similar to bone with respectto mineral content and has been identified as being bioactive and thusnot only supportive of bone ingrowth, but actively taking part in bonebonding.

With particular reference to FIGS. 1 and 4-9, the receiver 10 has agenerally U-shaped appearance with a partially discontinuous, partiallyfaceted and partially curved outer profile and partially cylindricalinner and outer profiles. The receiver 10 has an axis of rotation B thatis shown in FIG. 1 as being aligned with and the same as the axis ofrotation A of the shank 4, such orientation being desirable, but notrequired during assembly of the receiver 10 with the shank 4. After thereceiver 10 is pivotally attached to the shank 4, either before or afterthe shank 4 is implanted in a vertebra 17, the axis B is typicallydisposed at an angle with respect to the axis A, as shown, for example,in FIG. 46 that illustrates the assembly 1 with a manipulation andlocking tool.

The receiver 10 includes a curvate lower base portion 60 defining a boreor inner cavity, generally 61, the base 60 being integral with a pair ofopposed upstanding arms 62 forming a cradle and defining a channel 64between the arms 62 with an upper opening, generally 66, and asubstantially planar lower channel portion or seat 68, the channel 64having a width for operably receiving the rod 21 or portion of anotherlongitudinal connector between the arms 62, as well as closely receivinglaterally extending portions of the insert 14, the channel 64communicating with the base cavity 61. Inner opposed substantiallyplanar perimeter arm surfaces 69 partially define the channel 64 and arelocated on either side of each arm interior substantially cylindricalsurfaces generally 70. Lower opposed surface portions 71 of the armsurfaces 69 terminate at the lower seat 68. The arm interior surfaces70, each include various inner cylindrical profiles, an upper one ofwhich is a partial helically wound guide and advancement structure 72located adjacent top surfaces 73 of each of the arms 62. In theillustrated embodiment, the guide and advancement structure 72 is apartial helically wound interlocking flange form configured to mateunder rotation with a similar structure on the closure structure 18, asdescribed more fully below. However, it is foreseen that for certainembodiments of the invention, the guide and advancement structure 72could alternatively be a square-shaped thread, a buttress thread, areverse angle thread or other thread-like or non-thread-like helicallywound discontinuous advancement structures, for operably guiding underrotation and advancing the closure structure 18 downward between thearms 62, as well as eventual torquing when the closure structure 18abuts against the rod 21 or other longitudinal connecting member. It isforeseen that the arms 62 could have break-off extensions.

An opposed pair of upper rounded off triangular or delta-shaped toolreceiving and engaging apertures 74, each having a through bore formedby an upper arched surface 75 and a substantially planar bottom surface75′, are formed on outer surfaces 76 of the arms 62. Each through boresurface 75 and 75′ extends through the arm inner surface 70. Theapertures 74 with through bore portions 75 and 75′ are sized and shapedfor receiving locking, unlocking and other manipulation tools and in theillustrated embodiment, receives the retainer ring 12 (as shown inphantom in FIG. 21) during top loading of the retainer 12 into thereceiver 10 will be described in greater detail below. Each aperture 74further includes a sloping tool alignment surface 77 that surrounds thearched bore portion 75 and does not extend completely through therespective arm 62. It is noted that the receiver 10 is an integralstructure and devoid of any spring tabs or collet-like structures. Aswill be discussed in greater detail below, the geometry of the insert 14that extends outwardly into the receiver channel 64 at the perimeterarms surfaces 69 prohibits the insert 14 from rotating during assemblyand thus prohibits any misalignments with the receiver 10 and the rod 21or other longitudinal connecting member that sometimes occur with othertypes of compression inserts. The apertures 74 and additional toolreceiving apertures or grooves (not shown) may be used for holding thereceiver 10 during assembly with the insert 14, the retainer 12 and theshank 4; during the implantation of the shank body 6 into a vertebrawhen the shank is pre-assembled with the receiver 10; during assembly ofthe bone anchor assembly 1 with the rod 21 and the closure structure 18;and during lock and release adjustment of some inserts according to theinvention with respect to the receiver 10, either into or out offrictional engagement with the inner surfaces of the receiver 10 as willbe described in greater detail below. It is foreseen that tool receivinggrooves or apertures may be configured in a variety of shapes and sizesand be disposed at other locations on the receiver arms 62.

Returning to the interior surface 70 of the receiver arms 62, locatedbelow the guide and advancement structure 72 is a discontinuouscylindrical surface 80 partially defining a run-out feature for theguide and advancement structure 72. The cylindrical surface 80 has adiameter equal to or slightly greater than a greater diameter of theguide and advancement structure 72. Moving downwardly, in a directiontoward the base 60, following the cylindrical surface 80 of each arm isa cylindrical surface 82 located below an annular run-out seat orsurface 83 that extends inwardly toward the axis B and runsperpendicular or somewhat obliquely towards the axis B. The surface 82has a diameter smaller than the diameter of the surface 80. The surface82 is sized and shaped to initially closely receive and frictionallyhold a portion of the insert 14 as will be described in greater detailbelow. Located below the surface 82 is a discontinuous annular surfaceor narrow ledge 84 that is disposed substantially perpendicular to theaxis B. A partially discontinuous cylindrical surface 86 is located oneach arm below and adjacent to the ledge surface 84. The surface 86 hasa diameter larger than the diameter of the surface 82. A portion of theaperture surface 75 is adjacent to the cylindrical surface 86 at eacharm, the surface 86 otherwise terminating at a lower ledge 87. Apartially discontinuous cylindrical surface 88 is located on each armbelow and adjacent to the lower ledge 87. A diameter of the surface 88is larger than the diameter of the surface 86. The surface 88 terminatesat a lip 89 that extends inwardly toward the receiver axis B. Locatedbelow the lip 89 is a partially discontinuous cylindrical surface 90.The surface 90 also partially defines the inner cavity 61 generallybelow the apertures 74 at the surface 75′ and below the channel seat 68.The cylindrical surface 90 has a diameter slightly larger than thediameter of the discontinuous surface 88. The surface 90 terminates at acavity lower ledge surface 91 that extends outwardly away from the axisB and that may be perpendicular to the axis B, but is illustrated as afrusto-conical surface that extends both downwardly and outwardly awayfrom the axis B. The through bores 75 of the apertures 74 each extendthrough the arms at the surfaces 86, 88 and 90 with the sloping toolengagement walls 77 extending substantially on either side of each boresurface 75 and formed in the arm outer surfaces 76 at a locationprimarily opposite the inner surfaces 86 and 88.

With particular reference to FIGS. 1,5, 6 and 8, returning to thesubstantially planar peripheral surfaces 69, each arm 62 includes a pairof projecting ridges or stops 92, located on each surface 69, for atotal of four stops 92 that are located near the annular surface 87 andextend from front and back surfaces or arm faces 94 to the cylindricalsurface 88. The stops 92 of one arm 62 directly face the opposing pairof stops 92 on the other arm 62, each stop 92 projecting outwardly awayfrom the respective planar surface 69. The illustrated stops 92 areelongate and run in a direction perpendicular to the axis B. As will bedescribed in greater detail below, the stops 92 cooperate with surfacesof the insert 14 to retain the insert 14 within the channel 64 of thereceiver 10. In the illustrated embodiment, each stop 92 includes abottom surface or ledge 95 adjacent to a partially planar and partiallycurved surface 96. A planar portion of the surface 96 located directlybeneath the stop 92 is in line with or may be slightly inset from thesurface 69. Each set of opposed surfaces 96 curve toward one another andterminate at the respective adjacent lower surface portions 71. An edge97 defines a juncture of each curved surface 96 and the respectiveadjacent lower surface portion 71. A first width measured betweenopposing surface portions 71 is smaller than a second width measuredbetween opposed surfaces 69 located between the stops 92 and arm topsurfaces 73, providing opposed planar locking interference fit surfacesfor the insert 14′ as will be described in greater detail below. Theinsert 14 is sized and shaped to be closely received but slidablebetween the surfaces 71.

Returning to FIGS. 8 and 9, the annular or frusto-conical surface 91partially defines the base cavity 61 and is located below and adjacentto the cylindrical surface 90. Another cylindrical surface 99 is locatedbelow and adjacent to the surface 91. The surface 99 also defines aportion of the base cavity 61. The cylindrical surface 99 is orientedsubstantially parallel to the axis B and is sized and shaped to receivean expanded retainer ring 12. The surfaces 91 and 99 define acircumferential recess that is sized and shaped to receive the retainer12 as it expands around the shank upper portion 8 as the shank 8 movesupwardly through the receiver base and toward the channel 64 duringassembly. It is foreseen that the recess could be tapered or conical inconfiguration. A cylindrical surface 101 located below the cylindricalsurface 99 is sized and shaped to closely receive and surround a lowerportion of the retainer 12 when the retainer is in a substantiallyneutral position as shown in FIG. 37, for example. Thus, the cylindricalsurface 101 has a diameter smaller than the diameter of the cylindricalsurface 99 that defines the expansion area or expansion chamber for theretainer 12. The surface 101 is joined or connected to the surface 99 byone or more beveled, curved or conical surfaces 102. The surfaces 102allow for sliding and neutral or nominal positioning of the retainer 12into the space defined by the surface 101 and ultimate seating of theretainer 12 on a lower substantially horizontal annular surface 104located below and adjacent to the cylindrical surface 101. The annularsurface 104 is disposed substantially perpendicular to the axis B.

Located below and adjacent to the annular seating surface 104 is anothersubstantially cylindrical surface 106 that communicates with a beveledor flared bottom opening surface 107, the surface 107 communicating withan exterior base surface 108 of the base 60, defining a lower opening,generally 110, into the base cavity 61 of the receiver 10.

With particular reference to FIGS. 1 and 10-13, the lower open or splitretainer 12, that operates to capture the shank upper portion 8 withinthe receiver 10, has a central axis that is operationally the same asthe axis B associated with the receiver 10 when the shank upper portion8 and the retainer 12 are installed within the receiver 10. The retainerring 12 is made from a resilient material, such as a stainless steel ortitanium alloy, so that the retainer 12 may be expanded during varioussteps of assembly as will be described in greater detail below. Theretainer 12 has a central channel or hollow through bore, generally 121,that passes entirely through the ring 12 from a top surface 122 to abottom surface 124 thereof. Surfaces that define the channel or bore 121include a discontinuous inner cylindrical surface 125 adjacent the topsurface 122 and a discontinuous frusto-conical surface 127 adjacent thesurface 125, both surfaces coaxial when the retainer 12 is in a neutralnon-compressed, non-expanded orientation. An edge 128 is defined by thejuncture of the top surface 122 and the cylindrical surface 125. Asshown, for example, in FIG. 31, the shank upper portion 8 ultimatelyfrictionally engages the retainer 12 at the edge 128 when the assembly 1is locked into a final position. The retainer 12 further includes anouter cylindrical surface 130 located adjacent the top surface 122 andan outer beveled or frusto-conical surface 132 adjacent the bottomsurface 124. The surface 130 is oriented parallel to the central axis ofthe retainer 12. In some embodiments of the invention, spaced notches(not shown) may be formed in the cylindrical surface 130 to receive aholding and manipulation tool (not shown). In some embodiments furthernotches on inner or outer surfaces of the retainer may be made to evenlydistribute stress across the entire retainer 12 during expansionthereof.

The resilient retainer 12 further includes first and second endsurfaces, 134 and 135 disposed in spaced relation to one another whenthe retainer is in a neutral non-compressed state. The surface 134 and135 may also be touching when the retainer is in a neutral state. Bothend surfaces 134 and 135 are disposed substantially perpendicular to thetop surface 122 and the bottom surface 124. A width X between thesurfaces 134 and 135 is very narrow (slit may be made by EDM process) toprovide stability to the retainer 12 during operation. Because theretainer 12 is top loadable in a neutral state and the retainer 12 doesnot need to be compressed to fit within the receiver cavity 61, thewidth X may be much smaller than might be required for a bottom loadedcompressible retainer ring. The gap X functions only in expansion toallow the retainer 12 to expand about the shank upper portion 8. Thisresults in a stronger retainer that provides more surface contact withthe shank upper portion 8 upon locking, resulting in a sturdierconnection with less likelihood of failure than a retainer ring having agreater gap. Furthermore, because the retainer 12 is only expanded andnever compressed inwardly, the retainer 12 does not undergo themechanical stress that typically is placed on spring ring type retainersknown in the prior art that are both compressed inwardly and expandedoutwardly during assembly.

It is foreseen that in some embodiments of the invention, the retainer12 inner surfaces may include a roughening or additional material toincrease the friction fit against the shank upper portion 8 prior tolock down by the rod 21 or other longitudinal connecting member. Also,the embodiment shown in FIGS. 10-13 illustrates the surfaces 134 and 135as substantially parallel to the central axis of the retainer, however,it is foreseen that it may be desirable to orient the surfaces obliquelyor at a slight angle.

With particular reference to FIGS. 1 and 14-20, the friction fitcompression insert 14 is illustrated that is sized and shaped to bereceived by and down-loaded into the receiver 10 at the upper opening66. The compression insert 14 has an operational central axis that isthe same as the central axis B of the receiver 10. In operation, theinsert advantageously frictionally engages the bone screw shank upperportion 8, allowing for un-locked but non-floppy placement of the angleof the shank 4 with respect to the receiver 10 during surgery prior tolocking of the shank with respect to the receiver near the end of theprocedure. As will be described in greater detail below with respect tothe insert 14′ illustrated in FIGS. 34-40, in some embodiments of theinvention, the insert that has locked the shank 4 in a desired angularposition with respect to the receiver 10, by, for example, compressionfrom the rod 21 and closure top 18, is also forced into an interferencefit engagement with the receiver 10 at the pair of opposed receiverplanar arm surfaces 71 thereof and thus is capable of retaining theshank 6 in a locked position even if the rod 21 and closure top 18 areremoved. Such locked position may also be released by the surgeon ifdesired. The non-locking insert 14 as well as the locking insert 14′ arepreferably made from a solid resilient material, such as a stainlesssteel or titanium alloy, to provide for friction fit panels and also sothat arm portions of the insert may be pinched or pressed toward oneanother in some embodiments, such portions pressing outwardly againstthe receiver 10 during shipping and early stages of assembly.

The non-locking compression insert 14 includes a body 150 having apartially outer cylindrical surface and an inner U-shaped surface, theinsert having opposed ends, generally 151, the insert 14 being sized andshaped to extend completely through the U-shaped channel 64 between theopposed front and back surfaces or faces 94 of the arms 62 so as tocooperate with the receiver arm side surfaces 69, the stops 92, thesurfaces 96 and 71 below the stops 92 and the channel seat 68. AU-shaped channel surface or saddle 153 formed in the body 150 alsoextends between the insert ends 151 and when the insert 14 is assembledwith the receiver 10, the saddle 153 substantially aligns with thereceiver channel 64. The saddle 153 is formed by the insert body 150 andby two upstanding arms 156 and is sized and shaped to closely receivethe rod 21 or other longitudinal connecting member. It is foreseen thatan alternative insert embodiment may be configured to include planarholding surfaces that closely hold a square or rectangular bar as wellas hold a cylindrical rod-shaped, cord, or sleeved cord longitudinalconnecting member.

The insert 14 body 150 is thus integral with the pair of upstanding arms156 at an upper end thereof and is also integral with a downwardlyextending super structure illustrated as an opposed pair of crown colletextensions 158 at a lower end thereof, each super structure extension158 terminating at a slotted bottom surface 159. A bore, generally 160,is disposed primarily within and through the insert body 150 that runsalong the axis B and communicates with the U-shaped channel formed bythe saddle 153 and upstanding arms 156 and also runs between the colletextensions 158. The bore 160 is sized and shaped to provide space andclearance for shank driving and other manipulation tools.

The arms 156 that are disposed on either side of the saddle 153 extendupwardly therefrom and are sized and configured for ultimate placementbeneath and spaced from the closure top 118 within the receivercylindrical surfaces 86 and 88. Inner upper arm surfaces 157 extendupwardly and slightly outwardly from the remainder of the U-shapedsaddle 153. The arms 156 are also sized and shaped for resilienttemporary placement at the receiver cylindrical surface 82. The arms 156include outer lower convex surfaces 162 that are illustrated aspartially cylindrical, outer upper curved surfaces 163 adjacent thesurfaces 162, the surfaces 163 being curved and convex and also flaringoutwardly from either side of the body 150. The surfaces 163 areadjacent planar top surfaces 164 that are ultimately positioned inspaced relation with the closure top 18, so that the closure top 18frictionally engages the rod 21 only, pressing the rod 21 downwardlyagainst the insert saddle 153, the shank 4 upper portion 8 then pressingagainst the retainer 12 to lock the polyaxial mechanism of the bonescrew assembly 1 at a desired angle. Each of the top surfaces 164 slopesupwardly and away from the adjacent saddle surface 157.

Each partially cylindrical surface 162 located below the respectiveflared surface 163 extends from the surface 163 to a partially annularlower or bottom surface 165 of the insert body 150. Each surface 162 issized and shaped to generally fit within the receiver arms inner armsurfaces, generally 70. It is foreseen that in some embodiments of theinvention, the arms 156 may be extended and the top surfaces not slopedand the closure top configured such that the arms and, morespecifically, the arm top surfaces ultimately directly engage theclosure top 18 for locking of the polyaxial mechanism, for example, whenthe rod 21 is made from a deformable material. The arm outer surfaces162 further include notches or grooves formed thereon for receiving andengaging locking tools.

Specifically, in the illustrated embodiment, each surface 162 has av-notch or recess for receiving tooling, the notch defined by an uppersloping surface 167 and intersecting a lower planar surface 168 disposedsubstantially perpendicular to the central operational axis of theinsert 14. The surfaces 167 and 168 cooperate and align with therespective receiver aperture through bore 75, surface, and surface 75′when the insert 14 is captured and operationally positioned within thereceiver 10 as will be described in greater detail below. It is alsoforeseen that the arms 163 can extend upwardly and not be flared ortapered outwardly in some embodiments.

The insert 14 extends from the substantially cylindrical outer armssurfaces 162 equally outwardly to each end 151. Substantially planarouter side surfaces 170 extend from each arm surface 162 to asubstantially planar surface 171 disposed perpendicular thereto, thesurfaces 171 substantially defining each of the ends 151. Each endsurface 171 is adjacent to a lower extension surface 172 that runssubstantially parallel to the surface 165 and extends inwardly towardthe insert body 150. Adjacent to each side surface 170 is asubstantially planar upper or top surface 173 running from one of thearms 156 to each of the end surfaces 171. Each of the surfaces 170 forma narrow outer strip and are adjacent and perpendicular to a lowernarrow ledge 174. The ledges 174 run parallel to the upper surfaces 173.An inset planar surface 175 is adjacent to each lower ledge surface 174and runs parallel to the respective outer planar side surface 170. Awidth between opposing surfaces 175 is sized such that the surfaces 175are slidingly received between the opposed receiver lower arm surfaces71. In other embodiments of the invention, a width between the surfaces175 may be enlarged such that the surfaces 175 must be forced downwardlybetween the planar surfaces 71 to provide a locking non-contractile typeof interference fit of the insert against the receiver and thus lock thepolyaxial mechanism of the bone screw assembly as will be describedbelow with respect to the insert 14′. The surfaces 175 terminate atplanar end surfaces 177 and lower extension surfaces 178. A portion ofeach surface 175 extends all the way to the planar end surface 171.

The insert bore, generally 160, is substantially defined at the body 150by an inner substantially cylindrical surface 180 that communicates withthe saddle 153 and also communicates with a lower concave substantiallyspherical surface 181 having a radius the same or substantially similarto a radius of the surface 34 of the shank upper portion or head 8. Aportion of the surface 181 terminates at the body lower surface 165. Thesurface 181 also defines inner surfaces of the crown collet extensions158. Located along the spherical surface 181 between the cylindricalsurface 180 and the partially annular lower body surface 165 is a shankgripping surface portion 182. The gripping surface portion 182 includesone or more stepped surfaces or ridges sized and shaped to grip andpenetrate into the shank head 8 when the insert 14 is locked against thehead surface 34. It is foreseen that the stepped surface portion 182 mayinclude greater or fewer number of stepped surfaces and cover greater orless surface area of the spherical surface 181. It is foreseen that theshank gripping surface portion 182 and also the spherical surface 181may additionally or alternatively include a roughened or texturedsurface or surface finish, or may be scored, knurled, or the like, forenhancing frictional engagement with the shank upper portion 8.

The two collet extensions 158 that generally extend in a directionopposite to the two arms 156 and have the discontinuous inner sphericalsurface 181, also include through slits or slots 183 runningsubstantially vertically from adjacent the shank gripping surfaceportion 182 through the bottom surfaces 159. The illustrated embodimentincludes one slot 183 centrally located in each extension 158. It isforeseen that other embodiments of the invention may include more orfewer slots 183 or no slots. The slots 183 substantially equallypartition each of the extensions 158, forming four distinct resilient,partially spherical fingers, tab or panels 196 that extend from theshank gripping portion 182 to the bottom surface 159. In other words,the discontinuous inner spherical surface 181 is further separated intofour sections or panels 184, each having the discontinuous partiallyinner spherical surface 181 and having an outer surface 185 that issubstantially cylindrical in form. The panels 184 are sized and shapedto resiliently expand about the spherical surface 34 of the shank upperportion 8 and then snap on and frictionally grip the surface 34. In theillustrated embodiment, the spherical surface 181 is designed such thatthe gripping tabs or panels 184 have a neutral or non-expanded radiusthat is the same or slightly smaller than a radius of the shank surface34 so that when the tabs or panels 184 are gripping the surface 34, theinsert 14 collet extension portion 138 is in a neutral or slightlyexpanded state. In other embodiments, the non-expanded radius is thesame or larger than a radius of the shank surface. The contactingsurface area between the shank and the insert is sufficient to provide anon-floppy frictional fit in such instances. Furthermore, the shanksurface 34 and/or the spherical surface 181 may include a roughened orgrooved surface feature to provide for a frictional fit between theshank and the insert. In other embodiments, the resilient panels 184having a slightly larger pre-assembly radius than the shank surface 34and may be bent inwardly to result in a tighter frictional fit with theshank surface. When the shank 4 is locked into position by a rod 21 orother connecting member being pressed downwardly on the insert seat 153by the closure top 18, the insert 14 shank gripping portion 182 that isinitially slidable along the shank surface 34 then digs or penetratesinto the surface 34 and thus securely fixes the shank upper portion 8 tothe insert at the portion 182. It is foreseen that the sphericalsurfaces 181 could be flat or planar in some embodiments.

The bore 160 is sized and shaped to receive the driving tool (not shown)therethrough that engages the shank drive feature 46 when the shank body6 is driven into bone with the receiver 10 attached. Also, the bore 160may receive a manipulation tool used for releasing the alternativelocking insert 14′ from a locked position with the receiver, the toolpressing down on the shank and also gripping the insert 14′ at theopposed through bores 166′ or with other tool engaging features. Amanipulation tool for un-wedging the insert 14′ from the receiver 10 mayalso access the bores 166′ from the receiver through bores 74. Referringback to the insert 14, the outer notches defined by the surfaces 167 and168 may also receive tools extending through receiver through bores 74to temporarily lock the polyaxial mechanism as shown in FIGS. 46 and 48and described in greater detail below. The illustrated insert 14 mayfurther include other features, including additional grooves andrecesses for manipulating and holding the insert 14 within the receiver10 and providing adequate clearance between the retainer 12 and theinsert 14.

With reference to FIGS. 1 and 30-33, the illustrated elongate rod orlongitudinal connecting member 21 (of which only a portion has beenshown) can be any of a variety of implants utilized in reconstructivespinal surgery, but is typically a cylindrical, elongate structurehaving the outer substantially smooth, cylindrical surface 22 of uniformdiameter. The rod 21 may be made from a variety of metals, metal alloys,non-metals and deformable and less compressible plastics, including, butnot limited to rods made of elastomeric, polyetheretherketone (PEEK) andother types of materials, such as polycarbonate urethanes (PCU) andpolyethelenes.

Longitudinal connecting members for use with the assembly 1 may take avariety of shapes, including but not limited to rods or bars of oval,rectangular or other curved or polygonal cross-section. The shape of theinsert 14 may be modified so as to closely hold the particularlongitudinal connecting member used in the assembly 1. Some embodimentsof the assembly 1 may also be used with a tensioned cord. Such a cordmay be made from a variety of materials, including polyester or otherplastic fibers, strands or threads, such as polyethylene-terephthalate.Furthermore, the longitudinal connector may be a component of a longeroverall dynamic stabilization connecting member, with cylindrical orbar-shaped portions sized and shaped for being received by thecompression insert 14 of the receiver having a U-shaped, rectangular- orother-shaped channel, for closely receiving the longitudinal connectingmember. The longitudinal connecting member may be integral or otherwisefixed to a bendable or damping component that is sized and shaped to belocated between adjacent pairs of bone screw assemblies 1, for example.A damping component or bumper may be attached to the longitudinalconnecting member at one or both sides of the bone screw assembly 1. Arod or bar (or rod or bar component) of a longitudinal connecting membermay be made of a variety of materials ranging from deformable plasticsto hard metals, depending upon the desired application. Thus, bars androds of the invention may be made of materials including, but notlimited to metal and metal alloys including but not limited to stainlesssteel, titanium, titanium alloys and cobalt chrome; or other suitablematerials, including plastic polymers such as polyetheretherketone(PEEK), ultra-high-molecular weight-polyethylene (UHMWP), polyurethanesand composites, including composites containing carbon fiber, natural orsynthetic elastomers such as polyisoprene (natural rubber), andsynthetic polymers, copolymers, and thermoplastic elastomers, forexample, polyurethane elastomers such as polycarbonate-urethaneelastomers.

With reference to FIGS. 1 and 30-33, the closure structure or closuretop 18 shown with the assembly 1 is rotatably received between thespaced arms 62 of the receiver 10. It is noted that the closure 18 topcould be a twist-in or slide-in closure structure. The illustratedclosure structure 18 is substantially cylindrical and includes an outerhelically wound guide and advancement structure 193 in the form of aflange that operably joins with the guide and advancement structure 72disposed on the arms 62 of the receiver 10. The flange form utilized inaccordance with the present invention may take a variety of forms,including those described in Applicant's U.S. Pat. No. 6,726,689, whichis incorporated herein by reference. Although it is foreseen that theclosure structure guide and advancement structure could alternatively bea buttress thread, a square thread, a reverse angle thread or otherthread like or non-thread like helically wound advancement structure,for operably guiding under rotation and advancing the closure structure18 downward between the arms 62 and having such a nature as to resistsplaying of the arms 62 when the closure structure 18 is advanced intothe channel 64, the flange form illustrated herein as described morefully in Applicant's U.S. Pat. No. 6,726,689 is preferred as the addedstrength provided by such flange form beneficially cooperates with andcounters any reduction in strength caused by the any reduced profile ofthe receiver 10 that may more advantageously engage longitudinalconnecting member components. The illustrated closure structure 18 alsoincludes a top surface 194 with an internal drive 196 in the form of anaperture that is illustrated as a star-shaped internal drive such asthat sold under the trademark TORX, or may be, for example, a hex drive,or other internal drives such as slotted, tri-wing, spanner, two or moreapertures of various shapes, and the like. A driving tool (not shown)sized and shaped for engagement with the internal drive 196 is used forboth rotatable engagement and, if needed, disengagement of the closure18 from the receiver arms 62. It is also foreseen that the closurestructure 18 may alternatively include a break-off head designed toallow such a head to break from a base of the closure at a preselectedtorque, for example, 70 to 140 inch pounds. Such a closure structurewould also include a base having an internal drive to be used forclosure removal. A base or bottom surface 198 of the closure is planarand further includes a rim 199 for engagement and penetration into thesurface 22 of the rod 21 in certain embodiments of the invention. It isnoted that in some embodiments, the closure top bottom surface 198 mayinclude a central point and in other embodiments need not include apoint and/or the rim. The closure top 18 may further include acannulation through bore (not shown) extending along a central axisthereof and through the top and bottom surfaces thereof. Such a throughbore provides a passage through the closure 18 interior for a length ofwire (not shown) inserted therein to provide a guide for insertion ofthe closure top into the receiver arms 62.

An alternative closure top 218 for use with a deformable rod, such as aPEEK rod 221, is shown in FIGS. 41 and 42. The top 218 is identical tothe top 18 with the exception that a point or nub 289 is located on adomed surface 290 in lieu of the rim of the closure top 18. The closuretop 218 otherwise includes a guide and advancement structure 283, a top284, an internal drive 286 and a bottom outer annular surface 288 thatsame or substantially similar to the respective guide and advancementstructure 193, top 194, internal drive 196 and a bottom surface 198described herein with respect to the closure top 18. In someembodiments, the internal drive 286 is not as large as the drive 196 ofthe closure top 18, such smaller drive providing for less force beingplaced on a deformable rod, for example, and not being required when alocking insert, for example, the insert 14′ discussed below is utilizedin a bone screw assembly of the invention.

Returning to the assembly 1, preferably, the receiver 10, the retainer12 and the compression insert 14 are assembled at a factory setting thatincludes tooling for holding, alignment and manipulation of thecomponent pieces. In some circumstances, the shank 4 is also assembledwith the receiver 10, the retainer 12 and the compression insert 14 atthe factory. In other instances, it is desirable to first implant theshank 4, followed by addition of the pre-assembled receiver, retainerand compression insert at the insertion point. In this way, the surgeonmay advantageously and more easily implant and manipulate the shanks 4,distract or compress the vertebrae with the shanks and work around theshank upper portions or heads without the cooperating receivers being inthe way. In other instances, it is desirable for the surgical staff topre-assemble a shank of a desired size and/or variety (e.g., surfacetreatment of roughening the upper portion 8 and/or hydroxyapatite on theshank 6), with the receiver, retainer and compression insert. Allowingthe surgeon to choose the appropriately sized or treated shank 4advantageously reduces inventory requirements, thus reducing overallcost and improving logistics and distribution.

Pre-assembly of the receiver 10, retainer 12 and compression insert 14is shown in FIGS. 21-23. With particular reference to FIG. 21, first theretainer 12 is inserted into the upper receiver opening 66, leading withthe cylindrical surface 130 with the top surface 122 and the bottomsurface 124 facing opposed arms 62 of the receiver 10 (shown inphantom). The retainer 12 is then lowered in such sideways manner intothe channel 64, followed by tilting the retainer 12 at a location in thevicinity of the receiver apertures 74 such that the top surface 122 nowfaces the receiver opening 66 (also as shown in phantom). Thereafter,the retainer 12 is lowered into the receiver cavity 61 until the bottomsurface 124 is seated on the annular lower cavity seating surface 104 asshown in solid lines in FIG. 21.

With reference to FIGS. 22 and 23, the insert 14 is loaded into thereceiver 10. The insert 14 is loaded into the receiver through theopening 66 as shown in FIG. 22 with bottom surfaces 159 of the frictionfit crown collets 158 facing the receiver cavity 61 and the surfaces 170and 175 facing the planar arm surfaces 69 that define the channel 64 asthe insert 14 is lowered into the channel 64. When the insert 14 islowered into the receiver, the side surfaces 170 are slidingly receivedby the opposed receiver inner arm surfaces 69 defining the channel 64until the insert 14 reaches the stops 92. The insert 14 may be pressedfurther downwardly until the insert 14 is captured within the receiver10 as best shown in FIG. 23, with the surfaces 170 being slightlypinched or pressed inwardly toward the receiver axis B to allow theopposed surfaces 170 to engage and then move downwardly past thereceiver stops 92, the stops 92 thereafter prohibiting upward movementof the insert 14 out of the receiver channel 64. Specifically, if theinsert 14 is moved upwardly toward the opening 66 of the receiver, theinsert surfaces 173 abut against bottom surfaces 95 of the stops 92,prohibiting further upward movement of the insert 14 unless a tool isused to pinch the surfaces 170 toward one another while moving theinsert 14 upwardly toward the receiver opening 66.

With further reference to FIG. 23 and FIG. 24, the insert 14 does notdrop further downwardly toward the retainer 12 at this time because theouter arm surfaces 163 are engaged with and are slightly pressedinwardly by the receiver arm surfaces 82. The insert 14 is thus held inthe position shown in FIGS. 23 and 24 by the resilient arms 156 thereofresiliently pressing against the receiver inner cylindrical surfaces 82,which is a desired position for shipping as an assembly along with theseparate shank 4. Thus, the receiver 10, retainer 12 and insert 14combination is now pre-assembled and ready for assembly with the shank 4either at the factory, by surgery staff prior to implantation, ordirectly upon an implanted shank 4 as will be described herein.

As illustrated in FIG. 24, the bone screw shank 4 or an entire assembly1 made up of the assembled shank 4, receiver 10, retainer 12 andcompression insert 14, is screwed into a bone, such as the vertebra 17(shown in phantom), by rotation of the shank 4 using a suitable drivingtool (not shown) that operably drives and rotates the shank body 6 byengagement thereof at the internal drive 46. Specifically, the vertebra17 may be pre-drilled to minimize stressing the bone and have a guidewire (not shown) inserted therein to provide a guide for the placementand angle of the shank 4 with respect to the vertebra. A further taphole may be made using a tap with the guide wire as a guide. Then, thebone screw shank 4 or the entire assembly 1 is threaded onto the guidewire utilizing the cannulation bore 50 by first threading the wire intothe opening at the bottom 28 and then out of the top opening at thedrive feature 46. The shank 4 is then driven into the vertebra using thewire as a placement guide. It is foreseen that the shank and other bonescrew assembly parts, the rod 21 (also having a central lumen in someembodiments) and the closure top 18 (also with a central bore) can beinserted in a percutaneous or minimally invasive surgical manner,utilizing guide wires and attachable tower tools mating with thereceiver. When the shank 4 is driven into the vertebra 17 without theremainder of the assembly 1, the shank 4 may either be driven to adesired final location or may be driven to a location slightly above orproud to provide for ease in assembly with the pre-assembled receiver,compression insert and retainer.

With further reference to FIG. 24, the pre-assembled receiver, insertand retainer are placed above the shank upper portion 8 until the shankupper portion is received within the receiver opening 110. Withparticular reference to FIGS. 25-29, as the shank upper portion 8 ismoved into the interior 61 of the receiver base, the shank upper portion8 presses upwardly against the retainer 12, moving the retainer 12 intothe expansion portion of the receiver cavity 61 partially defined by theannular upper or ledge surface 91 and the cylindrical surface 99. As theportion 8 continues to move upwardly toward the channel 64, the surface34 forces outward movement of the retainer 12 towards the cylindricalsurface 99 as shown in FIG. 25, with upward movement of the retainer 12being prohibited by the annular surface 91. With reference to FIGS. 26and 27, the retainer 12 begins to return to its neutral state as thecenter of the sphere of the head 8 (shown in dotted lines) passes beyondthe center of the retainer expansion recess. With further reference toFIGS. 27-28, at this time also, the spherical surface 34 moves intoengagement with the discontinuous surface 181 of the insert 14 at theflex tabs or panels 184 of the crown collet extension portions 158. Thetabs 184 expand slightly outwardly to receive the surface 34 as bestshown in FIG. 28. With further reference to both FIG. 28 and FIG. 29,the spherical surface 34 then enters into full frictional engagementwith the panel inner surface 181. At this time, the insert 14 panels andthe surface 34 are in a fairly tight friction fit, the surface 34 beingpivotable with respect to the insert 14 with some force. Thus, a tight,non-floppy ball and socket joint is now created between the insert 14and the shank upper portion 8, even before the retainer 12 drops downinto a seated position on the receiver annular surface 104.

With reference to FIG. 29, the receiver may then be pulled upwardly orthe shank 4 and attached retainer 12 are then moved downwardly into adesired position with the retainer 12 seated on the surface 104. Again,this may be accomplished by either an upward pull on the receiver 10 or,in some cases, by driving the shank 4 further into the vertebra 17. Atthis time, the insert arms 156 spring outwardly into the receiversurface located beneath the ledge 84 and defined by the discontinuouscylindrical surface 86, making it impossible to move the insert 14upwardly without special tooling and making it impossible to move theretainer 12 out of the locking portion of the receiver chamber definedby the receiver seat 104 and the cylindrical surface 101. In someembodiments, when the receiver 10 is pre-assembled with the shank 4, theentire assembly 1 may be implanted at this time by inserting the drivingtool (not shown) into the receiver and the shank drive 46 and rotatingand driving the shank 4 into a desired location of the vertebra 17. Withreference to FIGS. 29 and 30 and also, for example, to FIGS. 46 and 48,at this time, the receiver 10 may be articulated to a desired angularposition with respect to the shank 4, that will be held, but not locked,by the frictional engagement between the insert 14 flex tabs 184 and theshank upper portion 8.

With reference to FIGS. 30-33, the rod 21 is eventually positioned in anopen or percutaneous manner in cooperation with the at least two bonescrew assemblies 1. The closure structure 18 is then advanced betweenthe arms 62 of each of the receivers 10. The closure structure 18 isrotated, using a tool engaged with the inner drive 196 until a selectedpressure is reached at which point the rod 21 engages the U-shapedseating surface 153 of the compression insert 14, pressing the steppedgripping surfaces 182 against the shank spherical surface 34, the edgesof the stepped surfaces 182 penetrating into the spherical surface 34,pressing the shank upper portion 8 into locked frictional engagementwith the retainer 12. Specifically, as the closure structure 18 rotatesand moves downwardly into the respective receiver 10, the rim 199engages and penetrates the rod surface 22, the closure structure 18pressing downwardly against and biasing the rod 21 into compressiveengagement with the insert 14 that urges the shank upper portion 8toward the retainer 12 inner body edge 128 and into locking engagementtherewith, the retainer 12 bottom surface 124 frictionally abutting thesurface 104 and the outer cylindrical surface 130 expanding outwardlyand abutting against the receiver cylindrical surface 101 that definesthe receiver locking chamber. For example, about 80 to about 120 inchpounds of torque on the closure top may be applied for fixing the bonescrew shank 6 with respect to the receiver 10. If disassembly if theassembly 1 is desired, such is accomplished in reverse order to theprocedure described previously herein for assembly.

With reference to FIGS. 34-40, an alternative lock-and-releasecompression insert 14′ is illustrated for use with the shank 4, receiver10, retainer 12, closure top 18 and rod 21 previously described herein,the resulting assembly identified as an assembly 1′ in FIGS. 39-40, forexample. The insert 14′ may be identical and is illustrated assubstantially similar to the insert 14 previously described herein, withthe exception that the insert 14′ is sized for a locking interferencefit with the edges 97 and adjacent planar surfaces 71 of the receiver 10as will be described in greater detail below. The illustrated insert 14′also differs from the insert 14 in that the insert 14′ includes toolreceiving apertures 166′ and does not have outwardly flared arms forresiliently engaging the receiver 10 during shipping and the earlyassembly steps.

Thus, the locking insert 14 includes a body 150′, a pair of opposed ends151′, a saddle surface 153′, a pair of arms 156′, a pair of arm uppersurfaces 157′, a pair of crown collet extensions 158′ having bottomsurfaces 159′, a bore 160′, outer cylindrical arm surfaces 162′, arm topsurfaces 164′, body bottom surfaces 165′, a pair of v-shaped aperturesthat include outer sloping surfaces 167′, and lower planar surfaces168′, extended portions with outer planar side surfaces 170′, planar endsurfaces 171′, a pair of base extensions 172′, upper surfaces 173′,narrow lower ledges 174′, inset planar side surfaces 175′, planar endsurfaces 177′, bottom surfaces 178′, an inner cylindrical surface 180′,an inner spherical surface 181′ and an inner gripping surface portion182′, slits 183′ and flex panels 184′ with outer surfaces 185′ that arethe same or substantially similar in form and function to the respectivebody 150, pair of opposed ends 151, saddle surface 153, pair of arms156, pair of arm upper surfaces 157, pair of crown collet extensions 158having bottom surfaces 159, bore 160, outer cylindrical arm surfaces162, arm top surfaces 164, body bottom surfaces 165, a pair of v-shapedapertures that include outer sloping surfaces 167, and lower planarsurfaces 168, extended portions with outer planar side surfaces 170,planar end surfaces 171, pair of base extensions 172, upper surfaces173, narrow lower ledges 174, inset planar side surfaces 175, planar endsurfaces 177, bottom surfaces 178, inner cylindrical surface 180, innerspherical surface 181, inner gripping surface portion 182, slits 183 andflex panels 184 with outer surfaces 185 previously described herein withrespect to the insert 14. As mentioned above, the insert 14′ does notinclude flared upper outer surfaces 163, but rather the cylindricalsurfaces 162′ extend from the top surfaces 164′ to the body lower orbottom surfaces 165′. Furthermore, the top arm surfaces 164′ are notsloping, but rather are planar surfaces disposed substantially parallelto the bottom surfaces 165′. The insert 14′ includes through holes 166′for receiving manipulation tools, the holes 166′ formed on the armsurfaces 162′ and located directly above and adjacent to the slopingsurfaces 167′.

The insert 14′ planar side surfaces 175′ are sized and shaped for alocking interference fit with the receiver at a lower portion of thereceiver channel 64. In other words, a width measured between surfaces175′ is sized large enough to require that the insert 14′ must be forcedinto the space between the receiver surfaces 71 starting at the edgesurfaces 97 by a tool or tools or by the closure top 18 forcing the rod21 downwardly against the insert 14′ with sufficient force tointerferingly lock the insert into the receiver between the planarsurfaces 71.

With reference to FIGS. 37-40, the insert 14′ is assembled with thereceiver 10, retainer 12, shank 4, rod 21 and closure top 18, in amanner the same as previously described above with respect to theassembly 1, resulting in an assembly 1′, with the exception that theinsert 14′ must be forced downwardly into a locking interference fitwith the receiver 10 when the shank 4 is locked in place, as compared tothe easily sliding relationship between the insert 14 and the receiver10. Also, the receiver arms 156′ do not engage the surfaces 82 of thereceiver 10. Rather, prior to assembly with the rod 21 and the closuretop 18, the compression insert 14′ outer surfaces 170′ are slidinglyreceived by receiver surfaces 71, but the surfaces 175′ are not. Theinsert 14′ is thus prohibited from moving any further downwardly at theedges 97 unless forced downwardly by a locking tool or by the closuretop pressing downwardly on the rod that in turn presses downwardly onthe insert 14′ as shown in FIGS. 38-40. With further reference to FIG.38, at this time, the receiver 10 may be articulated to a desiredangular position with respect to the shank 4, such as that shown inFIGS. 46 and 48, for example, that will be held, but not locked, by thefrictional engagement between the insert panels 184′ and the shank upperportion 8.

The rod 21 is eventually positioned in an open or percutaneous manner incooperation with the at least two bone screw assemblies 1′. The closurestructure 18 is then inserted into and advanced between the arms 62 ofeach of the receivers 10. The closure structure 18 is rotated, using atool engaged with the inner drive 196 until a selected pressure isreached at which point the rod 21 engages the U-shaped seating surface153′ of the compression insert 14′, further pressing the insert steppedshank gripping surfaces 182′ against the shank spherical surface 34, theedges of the stepped surfaces 182′ penetrating into the sphericalsurface 34, pressing the shank upper portion 8 into locked frictionalengagement with the retainer 12. Specifically, as the closure structure18 rotates and moves downwardly into the respective receiver 10, the rim199 engages and penetrates the rod surface 22, the closure structure 18pressing downwardly against and biasing the rod 21 into compressiveengagement with the insert 14′ that urges the shank upper portion 8toward the retainer 12 and into locking engagement therewith, theretainer 12 frictionally abutting the surface 104 and expandingoutwardly against the cylindrical surface 101. For example, about 80 toabout 120 inch pounds of torque on the closure top may be applied forfixing the bone screw shank 6 with respect to the receiver 10.Tightening the helical flange form to 100 inch pounds can create 1000pounds of force and it has been found that an interference fit iscreated between the planar surfaces 175′ of the insert 14′ and the edges97 and planar surfaces 71 of the receiver at between about 700-900 inchpounds. So, as the closure structure 18 and the rod 21 press the insert14′ downwardly toward the base of the receiver 10, the insert surfaces175′ are forced into the receiver at the edges 97, thus forcing andfixing the insert 14 into frictional interference engagement with thereceiver surfaces 71.

With reference to FIG. 41, at this time, the closure top 18 may beloosened or removed and/or the rod 21 may be adjusted and/or removed andthe frictional engagement between the insert 14′ and the receiver 10 atthe insert surfaces 175′ will remain locked in place, advantageouslymaintaining a locked angular position of the shank 4 with respect to thereceiver 10.

With further reference to FIGS. 41 and 42, at this time, another rod,such as the deformable rod 221 and cooperating alternative closure top218 may be loaded onto the already locked-up assembly to result in analternative assembly 201′. As mentioned above, the closure drive 286 mayadvantageously be made smaller than the drive of the closure 18, suchthat the deformable rod 221 is not unduly pressed or deformed duringassembly since the polyaxial mechanism is already locked.

With reference to FIGS. 43-45, a two-piece tool 600 is illustrated forreleasing the insert 14′ from the receiver 10. The tool 600 includes aninner flexible tube-like structure with opposed inwardly facing prongs612 located on either side of a through-channel 616. The channel 616 mayterminate at a location spaced from the prongs 612 or may extend furtherupwardly through the tool, resulting in a two-piece tool 610. The tool600 includes an outer, more rigid tubular member 620 having a smallerthrough channel 622. The member 620 slidingly fits over the tube 610after the flexible member 610 prongs 612 are flexed outwardly and thenfitted over the receiver 10 and then within through bores of the opposedapertures 74 of the receiver 10 and aligned opposed bores 166′ locatedon arms of the insert 14′. In FIG. 43, the tool 600 is shown during theprocess of unlocking the insert 14′ from the receiver 10 with the outermember 620 surrounding the inner member 610 and holding the prongs 612within the receiver 10 and insert 14′ apertures while the tool 600 ispulled upwardly away from the shank 4. It is foreseen that the tool 600may further include structure for pressing down upon the receiver 10while the prongs and tubular member are pulled upwardly, such structuremay be located within the tool 600 and press down upon the top surfaces73 of the receiver arms, for example.

Alternatively, another manipulation tool (not shown) may be used that isinserted into the receiver at the opening 66 and into the insert channelformed by the saddle 153′, with prongs or extensions thereof extendingoutwardly into the insert through bores 166′; a piston-like portion ofthe tool thereafter pushing directly on the shank upper portion 8,thereby pulling the insert 14′ away from the receiver surface 90 andthus releasing the polyaxial mechanism. At such time, the shank 4 may bearticulated with respect to the receiver 10, and the desired frictionfit returns between the insert 14 flex panels and the shank surface 34,so that an adjustable, but non-floppy relationship still exists betweenthe shank 4 and the receiver 10. If further disassembly if the assemblyis desired, such is accomplished in reverse order to the proceduredescribed previously herein for the assembly 1.

With reference to FIGS. 46-48, another manipulation tool, generally 700is illustrated for independently locking an insert 14′, or as shown, fortemporarily independently locking the non-locking insert 14 to thereceiver 10. The tool 700 includes a pair of opposed arms 712, eachhaving an engagement extension 716 positioned at an angle with respectto the respective arm 712 such that when the tool is moved downwardlytoward the receiver, one or more inner surfaces 718 of the engagementextension 716 slide along the surfaces 77 of the receiver and surfaces167 of the insert 14 to engage the insert 14, with a surface 720pressing downwardly on the insert surfaces 168 to lock the polyaxialmechanism of the assembly 1. As shown in FIG. 48, when the insert 14 islocked against the receiver 10, the tool bottom surfaces 720 do notbottom out on the receiver surfaces 75′, but remained spaced therefrom.In the illustrated embodiment, the surface 718 is slightly rounded andeach arm extension 716 further includes a planar lower surface 722 thatcreates an edge with the bottom surface 720 for insertion and grippingof the insert 14 at the juncture of the surface 167 and the surface 168.The tool 700 may include a variety of holding and pushing/pullingmechanisms, such as a pistol grip tool, that may include a ratchetfeature, a hinged tool, or, a rotatably threaded device, for example.

With reference to FIGS. 49-83 the reference number 1001 generallyrepresents another polyaxial bone screw apparatus or assembly accordingto the present invention. The assembly 1001 includes a shank 1004, thatfurther includes a body 1006 integral with an upwardly extending upperportion or head-like capture structure 1008; a receiver 1010; a retainerstructure illustrated as a resilient open ring 1012, and a friction fitcrown collet compression or pressure insert 1014. The receiver 1010,retainer 1012 and compression insert 1014 are initially assembled andmay be further assembled with the shank 1004 either prior or subsequentto implantation of the shank body 1006 into a vertebra 1017, as will bedescribed in greater detail below. FIGS. 49 and 82-83 further show aclosure structure 1018 for capturing a longitudinal connecting member,for example, a rod 1021 which in turn engages the compression insert1014 that presses against the shank upper portion 1008 into fixedfrictional contact with the retainer 1012, so as to capture, and fix thelongitudinal connecting member 1021 within the receiver 1010 and thusfix the member 1021 relative to the vertebra 1017. The illustrated rod1021 is substantially similar in form and function to the rod 21previously described herein. It is foreseen that in other embodiments,the rod 1021 may be elastic, deformable and/or of a differentcross-sectional geometry. The receiver 1010 and the shank 1004 cooperatein such a manner that the receiver 1010 and the shank 1004 can besecured at any of a plurality of angles, articulations or rotationalalignments relative to one another and within a selected range of anglesboth from side to side and from front to rear, to enable flexible orarticulated engagement of the receiver 1010 with the shank 1004 untilboth are locked or fixed relative to each other near the end of animplantation procedure.

The shank 1004, best illustrated in FIGS. 49-51, is elongate, with theshank body 1006 having a helically wound bone implantable thread 1024(single or dual lead thread form) extending from near a neck 1026located adjacent to the upper portion or head 1008, to a tip 1028 of thebody 1006 and extending radially outwardly therefrom. During use, thebody 1006 utilizing the thread 1024 for gripping and advancement isimplanted into the vertebra 1017 leading with the tip 1028 and drivendown into the vertebra with an installation or driving tool (not shown),so as to be implanted in the vertebra to a location at or near the neck1026. The shank 1004 has an elongate axis of rotation generallyidentified by the reference letter A.

The neck 1026 extends axially upward from the shank body 1006. The neck1026 may be of the same or is typically of a slightly reduced radius ascompared to an adjacent upper end or top 1032 of the body 1006 where thethread 1024 terminates. Further extending axially and outwardly from theneck 1026 is the shank upper portion or head 1008 that provides aconnective or capture apparatus disposed at a distance from the upperend 1032 and thus at a distance from the vertebra 1017 when the body1006 is implanted in such vertebra.

The shank upper portion 1008 is configured for a pivotable connectionbetween the shank 1004 and the retainer 1012 and receiver 1010 prior tofixing of the shank 1004 in a desired position with respect to thereceiver 1010. The shank upper portion 1008 has an outer, convex andsubstantially spherical surface 1034 that extends outwardly and upwardlyfrom the neck 1026 and terminates at a substantially planar top or rimsurface 1038. The spherical surface 1034 has an outer radius configuredfor frictional, non-floppy, sliding cooperation with a discontinuousconcave surface of the compression insert 1014, as well as ultimatefrictional engagement and penetration by a stepped, gripping portion ofthe insert 1014. The top surface 1038 is substantially perpendicular tothe axis A. The spherical surface 1034 shown in the present embodimentis substantially smooth, but in some embodiments may include aroughening or other surface treatment and is sized and shaped forcooperation and ultimate frictional engagement with the compressioninsert 1014 as well as ultimate frictional engagement with the retainer1012. The shank spherical surface 1034 is locked into place exclusivelyby the insert 1014 and the retainer 1012 and not by inner surfacesdefining the receiver cavity.

A counter sunk substantially planar base or stepped seating surface 1045partially defines an internal drive feature or imprint 1046. Theillustrated internal drive feature 1046 is an aperture formed in the topsurface 1038 and has a hex shape designed to receive a hex tool (notshown) of an Allen wrench type, into the aperture for rotating anddriving the bone screw shank 1004. It is foreseen that such an internaltool engagement structure may take a variety of tool-engaging forms andmay include one or more apertures of various shapes, such as a pair ofspaced apart apertures or a multi-lobular or star-shaped aperture, suchas those sold under the trademark TORX, or the like. The seat or basesurfaces 1045 of the drive feature 1046 are disposed substantiallyperpendicular to the axis A with the drive feature 1046 otherwise beingcoaxial with the axis A. As illustrated in FIGS. 50 and 51, the driveseat 1045 may include beveled or stepped surfaces that may furtherenhance gripping with the driving tool. In operation, a driving tool(not shown) is received in the internal drive feature 1046, being seatedat the base 1045 and engaging the six faces of the drive feature 1046for both driving and rotating the shank body 1006 into the vertebra1017, either before the shank 1004 is attached to the receiver 1010 orafter the shank 1004 is attached to the receiver 1010, with the shankbody 1006 being driven into the vertebra 1017 with the driving toolextending into the receiver 1010.

The shank 1004 shown in the drawings is cannulated, having a smallcentral bore 1050 extending an entire length of the shank 1004 along theaxis A. The bore 1050 is defined by an inner cylindrical wall of theshank 1004 and has a circular opening at the shank tip 1028 and an upperopening communicating with the external drive 1046 at the driving seat1045. The bore 1050 is coaxial with the threaded body 1006 and the upperportion 1008. The bore 1050 provides a passage through the shank 1004interior for a length of wire (not shown) inserted into the vertebra1017 prior to the insertion of the shank body 1006, the wire providing aguide for insertion of the shank body 1006 into the vertebra 1017. Theshank body 1006 may be treated or coated as previously described hereinwith respect to the shank body 6 of the assembly 1.

With particular reference to FIGS. 49 and 52-57, the receiver 1010 has agenerally U-shaped appearance with partially discontinuous and partiallycylindrical inner and outer profiles. The receiver 1010 has an axis ofrotation B that is shown in FIG. 49 as being aligned with and the sameas the axis of rotation A of the shank 1004, such orientation beingdesirable, but not required during assembly of the receiver 1010 withthe shank 1004 (see, e.g., FIG. 76 showing the receiver 1010 being“popped on” to a shank 1004 that is implanted in a vertebra 1017 anddisposed at an angle with respect to the receiver). After the receiver1010 is pivotally attached to the shank 1004, either before or after theshank 1004 is implanted in a vertebra 1017, the axis B is typicallydisposed at an angle With respect to the axis A, as shown, for example,in FIG. 96.

The receiver 1010 includes a substantially cylindrical base 1060defining a bore or inner cavity, generally 1061, the base 1060 beingintegral with a pair of opposed upstanding arms 1062 forming a cradleand defining a channel 1064 between the arms 1062 with an upper opening,generally 1066, and a U-shaped lower channel portion or seat 1068, thechannel 1064 having a width for operably snugly receiving the rod 1021or portion of another longitudinal connector, such as a sleeve of atensioned cord connector or other soft or dynamic connector between thearms 1062, the channel 1064 communicating with the base cavity 1061.Outer front and rear opposed substantially planar arm surfaces 1069partially define the channel 1064 directly above the seat 1068, thesurfaces 1069 advantageously reduce the run on the rod (i.e., provide amore narrow receiver portion that in turn provides more space and thusmore access between bone anchors along the rod or other connectingmember) and provide the planar surface 1069 for flush or close contactwith other connecting member components in certain embodiments, such assleeves, bumpers or spacers that cooperate with rods or cord-typeconnecting members.

Each of the arms 1062 has an interior surface, generally 1070, thatincludes various inner cylindrical profiles, an upper one of which is apartial helically wound guide and advancement structure 1072 locatedadjacent top surfaces 1073 of each of the arms 1062. In the illustratedembodiment, the guide and advancement structure 1072 is a partialhelically wound interlocking flange form configured to mate underrotation with a similar structure on the closure structure 1018, asdescribed more fully below. However, it is foreseen that for certainembodiments of the invention, the guide and advancement structure 1072could alternatively be a square-shaped thread, a buttress thread, areverse angle thread or other thread-like or non-thread-like helicallywound discontinuous advancement structures, for operably guiding underrotation and advancing the closure structure 1018 downward between thearms 1062, as well as eventual torquing when the closure structure 1018abuts against the rod 1021 or other longitudinal connecting member. Itis foreseen that the arms could have break-off extensions.

An opposed pair of upper rounded off triangular or delta-shaped toolreceiving and engaging apertures, generally 1074, each having a throughbore formed by an upper arched surface 1075 and a substantially planarbottom surface 1075′, are formed on outer surfaces 1076 of the arms1062. Each through bore surface 1075 and 1075′ extends through the arminner surface 1070. The apertures 1074 with through bore portions 1075and 1075′ are sized and shaped for receiving locking, unlocking andother manipulation tools and may aid in receiving and downloading theretainer ring 1012 during top loading of the retainer 1012 into thereceiver 1010. Each aperture 1074 further includes a sloping toolalignment surface 1077 that surrounds the arched bore portion 1075 anddoes not extend completely through the respective arm 1062. In thepresent embodiment, part of the receiver defining the surface 1077located along the arched aperture portion is crimped into the insert1014 during assembly thereof with the receiver 1010 as will be describedin greater detail below. In other embodiments of the invention, otherwalls or surfaces defining the aperture 1074 or other material definingother apertures or grooves may be inwardly crimped. It is noted that theillustrated receiver 1010 is an integral structure and devoid of anyspring tabs or collet-like structures. Alternatively, in someembodiments, spring tabs or other movable structure may be included onthe receiver 1010 or the insert 1014 for retaining the insert 1014 in adesired position, with regard to rotation and axial movement (along theaxis A) with respect to the receiver 1010. Preferably the insert and/orreceiver are configured with structure for blocking rotation of theinsert with respect to the receiver, but allowing some up and downmovement of the insert with respect to the receiver during the assemblyand implant procedure.

Located directly centrally above each delta shaped aperture 1074 is acylindrical depression or aperture 1078, also formed in each arm surface1076, but not extending through the inner surface 1070. Two additionalpair of tool receiving and engaging apertures 1079 are also formed inthe front and rear surfaces 1069 of the receiver arms 1062. Transitionbase surfaces 1080 span between the planar surfaces 1069 at the U-shapedseat 1068 and the cylindrical base 1060, the surfaces 1080 slopingdownwardly toward the base 1060 at an angle with respect to the axis B.Some or all of the apertures 1074, 1078 and 1079 may be used for holdingthe receiver 1010 during assembly with the insert 1014, the retainer1012 and the shank 1004; during the implantation of the shank body 1006into a vertebra when the shank is pre-assembled with the receiver 1010;during assembly of the bone anchor assembly 1001 with the rod 1021 andthe closure structure 1018; and during lock and release adjustment ofthe some inserts of the invention with respect to the receiver 1010,either into or out of frictional engagement with the inner surfaces ofthe receiver 1010 as will be described in greater detail below. It isforeseen that tool receiving grooves, depressions or apertures may beconfigured in a variety of shapes and sizes and be disposed at otherlocations on the receiver arms 1062.

Returning to the interior surface 1070 of the receiver arms 1062,located below the guide and advancement structure 1072 is adiscontinuous cylindrical surface 1082 partially defining a run-outfeature for the guide and advancement structure 1072. The cylindricalsurface 1082 has a diameter equal to or slightly greater than a greaterdiameter of the guide and advancement structure 1072. Moving downwardly,in a direction toward the base 1060, adjacent the cylindrical surface1082 of each arm is a run-out seat or surface 1084 that extends inwardlytoward the axis B and slopes toward the axis B. Adjacent to and locatedbelow the surface 1084 is another cylindrical surface 1086 having adiameter smaller than the diameter of the surface 1082. The through boresurfaces 1075 and 1075′ extend through the arms primarily at thesurfaces 1086, with an upper portion of each arch 1075 extending throughone of the surfaces 1082. Located near each aperture surface 1075 is aninner surface portion 1087 that engages the insert 1014 when the thinwall at the surface 1077 is crimped toward the insert 1014 duringassembly of such insert in the receiver 1010 as will be described ingreater detail below. A continuous annular surface 1088 is located belowand adjacent to the cylindrical surface 1086. The otherwisediscontinuous cylindrical surface 1086 that partially forms the receiverarms 1062 is also continuous at and near the interface between thesurface 1086 and the annular surface 1088, forming an upper portion ofthe receiver cavity 1061. The surface 1088 is disposed substantiallyperpendicular or slopes inwardly toward the axis B. A continuous innercylindrical surface 1090 is adjacent the annular surface 1088 andextends downwardly into the receiver base 1060. The surface 1090 isdisposed parallel to the receiver axis B. The surface 1090 has adiameter slightly smaller than the diameter of the surface 1086. Thecylindrical surfaces 1086 and 1090 are sized to receive portions of theinsert 1014, and as will be described in greater detail below, in someembodiments provide a locking interference fit with a cylindricalportion of a locking insert.

Now, with respect to the base 1060 and more specifically, the basecavity 1061, a lower portion of the surface 1090 that extends into thebase and partially defines the base cavity 1061 terminates at an annularsurface or ledge 1095. The ledge 1095 extends outwardly away from theaxis B and is substantially perpendicular thereto.

Extending downwardly from the ledge 1095 is a cylindrical surface 1099that partially defines the base cavity 1061 and in particular, definesan expansion chamber for the retainer 1012. The cylindrical surface 1099is oriented substantially parallel to the axis B and is sized and shapedto receive an expanded retainer 1012. The surfaces 1095 and 1099 definea circumferential recess that is sized and shaped to receive theretainer 1012 as it expands around the shank upper portion 1008 as theshank 1004 moves upwardly toward the channel 1064 during assembly, aswell as form a stop or restriction to prevent the expanded retainer 1012from moving upwardly with the shank portion 1008, the surface 1095preventing the retainer 1012 from passing upwardly out of the cavity1061 whether the retainer 1012 is in a partially or fully expandedposition or state. A cylindrical surface 1101 located below thecylindrical surface 1099 is sized and shaped to closely receive theretainer 1012 when the retainer is in a neutral position as shown inFIG. 71, for example. Thus, the cylindrical surface 1101 has a diametersmaller than the diameter of the cylindrical surface 1099 that definesthe expansion area for the retainer 1012. The surface 1101 is joined orconnected to the surface 1099 by one or more beveled, curved or conicalsurfaces 1102. The surfaces 1102 allow for sliding gradual movement ofthe retainer 1012 into the space or locking chamber defined by thesurface 1101 and ultimate seating of the retainer 1012 on a lowerannular surface 1104 located below and adjacent to the cylindricalsurface 1101.

Located below and adjacent to the annular seating surface 1104 isanother substantially cylindrical surface 1106 that communicates with abeveled or flared bottom opening surface 1107, the surface 1107communicating with an exterior base surface 1108 of the base 1060,defining a lower opening, generally 1110, into the base cavity 1061 ofthe receiver 1010.

With particular reference to FIGS. 49 and 58-62, the lower open or splitretainer 1012, that operates to capture the shank upper portion 1008within the receiver 1010, has a central axis that is operationally thesame as the axis B associated with the receiver 1010 when the shankupper portion 1008 and the retainer 1012 are installed within thereceiver 1010. The retainer ring 1012 is made from a resilient material,such as a stainless steel or titanium alloy, so that the retainer 1012may be expanded during various steps of assembly as will be described ingreater detail below. The retainer 1012 has a central channel or hollowthrough bore, generally 1121, that passes entirely through the ring 1012from a top surface 1122 to a bottom surface 1124 thereof. Surfaces thatdefine the channel or bore 1121 include a discontinuous innercylindrical surface 1125 adjacent the top surface 1122 and adiscontinuous frusto-conical surface 1127 adjacent the surface 1125,both surfaces coaxial when the retainer 1012 is in a neutral,non-expanded orientation. An edge 1128 is defined by the juncture of thetop surface 1122 and the cylindrical surface 1125. The edge 1128 mayinclude a chamfer or bevel. As shown, for example, in FIG. 82, the shankupper portion 1008 ultimately frictionally engages the retainer 1012 atthe edge 1128 when the assembly 1001 is locked into a final position.The retainer 1012 further includes an outer cylindrical surface 1130located adjacent the top surface 1122 and an outer beveled orfrusto-conical surface 1132 adjacent the bottom surface 1124. Thesurface 1130 is oriented parallel to the central axis of the retainer1012. In some embodiments of the invention, spaced notches (not shown)may be formed in the cylindrical surface 1130 to receive a holding andmanipulation tool (not shown). In some embodiments further notches oninner or outer surfaces of the retainer may be made to evenly distributestress across the entire retainer 1012 during expansion thereof.

The resilient retainer 1012 further includes first and second endsurfaces, 1134 and 1135 disposed in spaced relation to one another whenthe retainer is in a neutral non-compressed state. The surface 1134 and1135 may also be touching when the retainer is in a neutral state. Bothend surfaces 1134 and 1135 are disposed substantially perpendicular tothe top surface 1122 and the bottom surface 1124. A width X between thesurfaces 1134 and 1135 is very narrow (slit may be made by EDM process)to provide stability to the retainer 1012 during operation. Because theretainer 1012 is top loadable in a neutral state and the retainer 1012does not need to be compressed to fit within the receiver cavity 1061,the width X may be much smaller than might be required for a bottomloaded compressible retainer ring. The gap X functions only in expansionto allow the retainer 1012 to expand about the shank upper portion 1008.This results in a stronger retainer that provides more surface contactwith the shank upper portion 1008 upon locking, resulting in a sturdierconnection with less likelihood of failure than a retainer ring having agreater gap. Furthermore, because the retainer 1012 is only expanded andnever compressed inwardly, the retainer 1012 does not undergo themechanical stress that typically is placed on spring ring type retainersknown in the prior art that are both compressed inwardly and expandedoutwardly during assembly.

It is foreseen that in some embodiments of the invention, the retainer1012 inner surfaces may include a roughening or additional material toincrease the friction fit against the shank upper portion 1008 prior tolock down by the rod 1021 or other longitudinal connecting member. Also,the embodiment shown in FIGS. 58-62 illustrates the surfaces 1134 and1135 as substantially parallel to the central axis of the retainer,however, it is foreseen that it may be desirable to orient the surfacesobliquely or at a slight angle.

With particular reference to FIGS. 49 and 63-70, the friction fit, crowncompression insert 1014 is illustrated that is sized and shaped to bereceived by and down-loaded into the receiver 1010 at the upper opening1066. The compression insert 1014 has an operational central axis thatis the same as the central axis B of the receiver 1010. In operation,the insert advantageously frictionally engages the bone screw shankupper portion 1008, allowing for un-locked but non-floppy placement ofthe angle of the shank 1004 with respect to the receiver 1010 duringsurgery prior to locking of the shank with respect to the receiver nearthe end of the procedure. As will be described in greater detail belowwith respect to the insert 1014′ illustrated in FIGS. 84-92, in someembodiments of the invention, the insert that has locked the shank 1004in a desired angular position with respect to the receiver 1010, by, forexample, compression from the rod 1021 and closure top 1018, is alsoforced into an interference fit engagement with the receiver 1010 at theinner cylindrical surface 1090 and thus is capable of retaining theshank 1006 in a locked position even if the rod 1021 and closure top1018 are removed. Such locked position may also be released by thesurgeon if desired. The non-locking insert 1014 as well as the lockinginsert 1014′ are preferably made from a solid resilient material, suchas a stainless steel or titanium alloy, so that portions of the insertmay be snapped or popped onto the shank upper portion 1008 as well aspinched or pressed against and un-wedged from the receiver 1010 with arelease tool.

The non-locking crown collet compression insert 1014 includes asubstantially cylindrical body 1136 integral with a pair of upstandingarms 1137 at an upper end thereof and integral with downwardly extendingresilient superstructure in the form of an opposed pair of crown Colletextensions 1138 at a lower end thereof. A bore, generally 1140, isdisposed primarily within and through the body 1136 and communicateswith a generally U-shaped through channel formed by a saddle 1141 thatis partially defined by the upstanding arms 1137 and partially by thebody 1136. The saddle 1141 is sized and shaped to closely, snugly engagethe cylindrical rod 1021 and includes a curved lower seat 1142. It isforeseen that an alternative embodiment may be configured to includeplanar holding surfaces that closely hold a square or rectangular bar aswell as hold a cylindrical rod-shaped, cord, or sleeved cordlongitudinal connecting member. The arms 1137 disposed on either side ofthe saddle 1141 extend upwardly from the body 1136. The arms 1137 aresized and configured for ultimate placement at or near the cylindricalrun-out surface 1082 and inner surfaces 1084 and 1086 located below thereceiver guide and advancement structure 1072. It is foreseen that insome embodiments of the invention, the insert arms 1137 may be extendedand the closure top configured such the arms ultimately directly engagethe closure top 1018 for locking of the polyaxial mechanism, forexample, when the rod 1021 is made from a deformable material. In suchembodiments, the insert 1014 would include a rotation blocking structureor feature on an outer surface thereof that abuts against cooperatingstructure located on an inner wall of the receiver 1010, preventingrotation of the insert with respect to the receiver when the closure topis rotated into engagement with the insert. In the present embodiment,the arms 137 include outer surfaces 1143 that are illustrated aspartially cylindrical and run from substantially planar top surfaces1144 to near bottom surfaces 1148 of the collet extensions 1138, the topsurfaces 1144 ultimately being positioned in spaced relation with theclosure top 1018, so that the closure top 1018 frictionally engages therod 1021 only, pressing the rod 1021 downwardly against the seatingsurface 1142, the insert 1014 in turn pressing against the shank 1004upper portion 1008 that presses against the retainer 1012 to lock thepolyaxial mechanism of the bone screw assembly 1001 at a desired angle.Specifically, the illustrated partially cylindrical surfaces 1143 eachextend from one of the arm top surfaces 1144 to a rim or ledge 1150spaced from the bottom surfaces 1148 of the collet extensions 1138. Eachrim or ledge 1150 is positioned near an annular lower surface 1151 ofthe insert body 1136. Located between each rim 1150 and each extensionbottom surface 1148 is a discontinuous outer cylindrical surface 1152partially defining each collet extension 1138 and having an outerdiameter smaller than a diameter of the arm cylindrical surfaces 1143. Athrough slot 1154 is centrally formed in each collet extension 1138extending through the extension at the bottom surface 1148, the outercylindrical surface 1152 and partially into the outer cylindricalsurface 1143 at the insert body 1136. The illustrated embodimentincludes the one slot 1154 centrally located in each extension 1138. Itis foreseen that other embodiments of the invention may include more orfewer slots 1154. The slots 1154 substantially equally partition each ofthe extensions 1138, forming four distinct resilient, fingers, tabs orpanels 1154 that extend to the bottom surface 1148.

The surfaces 1143 are sized and shaped to generally fit within thereceiver arms 1062. The arm outer surfaces 1143 further include notchesor grooves formed thereon for receiving manipulation, unlocking andlocking tools. Although not shown, each surface 1143 may include one ormore through bores or other apertures for receiving tooling, such asthat shown on the locking insert 1014′ in FIG. 84, for example.Centrally located (in some embodiments below a through bore) and formedin each surface 1143 is a delta or triangular notch or recess, generally1156, for receiving tooling defined in part by an upper sloping surface1157 and intersecting a lower planar surface 1158 disposed substantiallyperpendicular to a central axis of the insert 1014 (and the axis B ofthe receiver when the insert is disposed within the receiver). Each ofthe surfaces 1167 and surface 1168 cooperate and align with therespective receiver aperture through bore surfaces 1077 and 1075′ whenthe insert 1014 is captured and operationally positioned within thereceiver 1010 as will be described in greater detail below. In theillustrated embodiments, also formed in each surface 1143 are a pair ofspaced v- or squared-off notches or grooves 1160 and 1161 that run fromthe respective top surface 1144 to near the surface 1158 of the centraldelta cut or notch 1156. The grooves 1160 and 1161 cooperate with thereceiver crimp wall inner surfaces 1087 to aid in alignment of theinsert channel saddle 1141 with the receiver channel 1064 as shown, forexample in FIGS. 74 and 75. The illustrated pair of grooves 1160 and1161 slope slightly toward one another as best shown in FIG. 66, runningfrom respective bottom surfaces 1162 and 1163 to a closest location atthe arm top surface 1144.

The u-shaped channel formed by the saddle 1141 is also partially definedby inner planar surfaces 1165 located near the arm top surfaces 1144.The saddle 1141 also communicates with the bore 1140 at an innercylindrical surface 1166, the surface 1166 located centrally within theinsert body 1136 and further communicating with a lower collet spacethat extends to the discontinuous bottom surfaces 1148 of the colletextensions 1138. The inner cylindrical surface 1166 also communicateswith a lower concave surface portion 1168 having a generally sphericalprofile with a radius the same or substantially similar to a radius ofthe surface 1034 of the shank upper portion or head 1008. The surface1168 primarily terminates at the body lower surface 1151, but alsoextends into and partially defines inner surfaces of the colletextensions 1138. Located along the inner surface 1168 between thecylindrical surface 1166 and the body lower surface 1151 is a shankgripping surface portion 1170. The gripping surface portion 1170includes one or more stepped surfaces or ridges sized and shaped to gripand penetrate into the shank head 1008 when the insert 1014 is lockedagainst the head surface 1034. In the illustrated embodiments,substantially all the inner surface 1168 is made up of stepped portionsand thus the entire surface may also be described as having a pluralityof cylindrical surfaces of graduating diameters. It is foreseen that thestepped surface portion 1170 may include a greater or fewer number ofstepped surfaces and cover greater or less surface area of the innersurface 1168 having the same or similar spherical profile as the surface1034 of the shank head 1008. It is foreseen that any and all of theshank gripping surface portion 1170 and the surface 1168 mayadditionally or alternatively include a roughened or textured surface orsurface finish, or may be scored, knurled, or the like, for enhancingfrictional engagement with the shank upper portion 1008. Located belowthe body lower surface 1151, each collet extension 1138 includes a pairof inner upper curved portion 1172 and a pair of planar surface portion1173, each planar surface portion 1173 located between an adjacentcurved portion 1172 and adjacent respective bottom surface 1148. Theplanar surface portion 1173 are sized, shaped and positioned withrespect to one another to provide a non-locking frictional fit with thespherical surface 1034 of the shank upper portion or head 1008 as willbe described in greater detail below. It is foreseen that in someembodiments of the invention, the planar surfaces 1173 may be replacedby radiused surfaces having the same, greater or lesser radius than theshank surface 1034.

The insert bore 1140 is sized and shaped to receive the driving tool(not shown) therethrough that engages the shank drive feature 46 whenthe shank body 1006 is driven into bone with the receiver 1100 attached.Also, the bore 1140 may receive a manipulation tool used for releasingthe alternative locking insert 1014′ from a locked position with thereceiver, the tool pressing down on the shank and also gripping theinsert 1014′ at the opposed through bores or with other tool engagingfeatures. A manipulation tool for un-wedging the insert 1104′ from thereceiver 1100 may also access the such tooling bores from the receiverthrough bores 1074. The illustrated insert 1014 may further includeother features, including grooves and recesses for manipulating andholding the insert 1014 within the receiver 1010 and providing adequateclearance between the retainer 1012 and the insert 1014.

The insert body 1136 located between the arms 1137 and the colletextensions 1138 has an outer diameter slightly smaller than a diameterbetween crests of the guide and advancement structure 1072 of thereceiver 1010, allowing for top loading of the compression insert 1014into the receiver opening 1066, with the arms 1137 of the insert 1014being located between the receiver arms 6102 during insertion of theinsert 1014 into the receiver 1010. Once the arms 1137 of the insert1014 are generally located beneath the guide and advancement structure1072, the insert 1014 is rotated into place about the receiver axis Buntil the top surfaces 1144 are located directly below the guide andadvancement structure 1072 as will be described in greater detail below.

With reference to FIGS. 49 and 82-83, the illustrated elongate rod orlongitudinal connecting member 1021 (of which only a portion has beenshown) can be any of a variety of implants utilized in reconstructivespinal surgery, but is typically a cylindrical, elongate structurehaving the outer substantially smooth, cylindrical surface 1022 ofuniform diameter. The illustrated rod 1021 is identical or substantiallysimilar to the rod 21 previously described herein. Other longitudinalconnecting members for use with the assembly 1001 may take a variety ofshapes, including but not limited to rods or bars of oval, rectangularor other curved or polygonal cross-section. The shape of the insert 1014may be modified so as to closely hold, and if desired, fix or slidinglycapture the longitudinal connecting member to the assembly 1001. Someembodiments of the assembly 1001 may also be used with a tensioned cord.Such a cord may be made from a variety of materials, including polyesteror other plastic fibers, strands or threads, such aspolyethylene-terephthalate. Furthermore, the longitudinal connector maybe a component of a longer overall dynamic stabilization connectingmember, with cylindrical or bar-shaped portions sized and shaped forbeing received by the compression insert 1014 of the receiver having aU-shaped, rectangular- or other-shaped channel, for closely receivingthe longitudinal connecting member. The longitudinal connecting membermay be integral or otherwise fixed to a bendable or damping componentthat is sized and shaped to be located between adjacent pairs of bonescrew assemblies 1001, for example. A damping component or bumper may beattached to the longitudinal connecting member at one or both sides ofthe bone screw assembly 1001. A rod or bar (or rod or bar component) ofa longitudinal connecting member may be made of a variety of materialsranging from non-metallic materials, such as soft deformable plastics,to hard metals, depending upon the desired application. Thus, bars androds of the invention may be made of materials including, but notlimited to metal and metal alloys including but not limited to stainlesssteel, titanium, titanium alloys and cobalt chrome; or other suitablematerials, including plastic polymers such as polyetheretherketone(PEEK), ultra-high-molecular weight-polyethylene (UHMWP), polyurethanesand composites, including composites containing carbon fiber, natural orsynthetic elastomers such as polyisoprene (natural rubber), andsynthetic polymers, copolymers, and thermoplastic elastomers, forexample, polyurethane elastomers such as polycarbonate-urethaneelastomers.

With reference to FIGS. 49 and 82-83, the closure structure or closuretop 1018 shown with the assembly 1001 is identical or substantiallysimilar to the closure top 18 previously described herein with respectto the assembly 1. It is noted that the closure 1018 top could be atwist-in or slide-in closure structure. The illustrated closurestructure 1018 is substantially cylindrical and includes a an outerhelically wound guide and advancement structure 1182 in the form of aflange that operably joins with the guide and advancement structure 1072disposed on the arms 1062 of the receiver 1010. The illustrated closurestructure 1018 also includes a top surface 1184 with an internal drive1186 in the form of an aperture that is illustrated as a star-shapedinternal drive such as that sold under the trademark TORX, or may be,for example, a hex drive, or other internal drives such as slotted,tri-wing, spanner, two or more apertures of various shapes, and thelike. A driving tool (not shown) sized and shaped for engagement withthe internal drive 1166 is used for both rotatable engagement and, ifneeded, disengagement of the closure 1018 from the receiver arms 1062.It is also foreseen that the closure structure 1018 may alternativelyinclude a break-off head designed to allow such a head to break from abase of the closure at a preselected torque, for example, 70 to 140 inchpounds. Such a closure structure would also include a base having aninternal drive to be used for closure removal. A base or bottom surface1188 of the closure is planar and further includes a rim 1190 and may ormay not include a further include a central point (not shown), the rim1190 and or the point (not shown) for engagement and penetration intothe surface 1022 of the rod 1021 in certain embodiments of theinvention. The closure top 1018 may further include a cannulationthrough bore (not shown) extending along a central axis thereof andthrough the top and bottom surfaces thereof. Such a through boreprovides a passage through the closure 1018 interior for a length ofwire (not shown) inserted therein to provide a guide for insertion ofthe closure top into the receiver arms 1062.

An alternative closure top 1218 for use with a deformable rod, such as aPEEK rod 1221, is shown in FIGS. 91 and 92. The top 2118 is identical tothe top 1018 with the exception that a point or nub 1289 is located on adomed surface 1290 in lieu of the rim of the closure top 1018. Theclosure top 1218 otherwise includes a guide and advancement structure1283, a top 1284, an internal drive 1286 and a bottom outer annularsurface 1288 that are the same or substantially similar to the guide andadvancement structure 1183, top 1184, internal drive 1186 and a bottomsurface 1188 described herein with respect to the closure top 1018. Insome embodiments, the internal drive 1286 is not as large as the drive1186 of the closure top 1018, such smaller drive providing for lessforce being placed on a deformable rod, for example, and not beingrequired when a locking insert, for example, the insert 1014′ discussedbelow is utilized in a bone screw assembly of the invention.

Returning to the assembly 1110, preferably, the receiver 1010, theretainer 1012 and the compression insert 1014 are assembled at a factorysetting that includes tooling for holding, pressing and alignment of thecomponent pieces as well as compressing or expanding the insert 1014arms and/or collet extensions, if needed, as well as crimping a portionof the receiver 1010 toward the insert 1014. In some circumstances, theshank 1004 is also assembled with the receiver 1010, the retainer 1012and the compression insert 1014 at the factory. In other instances, itis desirable to first implant the shank 1004, followed by addition ofthe pre-assembled receiver, retainer and compression insert at theinsertion point. In this way, the surgeon may advantageously and moreeasily implant and manipulate the shanks 1004, distract or compress thevertebrae with the shanks and work around the shank upper portions orheads without the cooperating receivers being in the way. In otherinstances, it is desirable for the surgical staff to pre-assemble ashank of a desired size and/or variety (e.g., surface treatment ofroughening the upper portion 1008 and/or hydroxyapatite on the shank1006), with the receiver, retainer and compression insert. Allowing thesurgeon to choose the appropriately sized or treated shank 1004advantageously reduces inventory requirements, thus reducing overallcost.

Pre-assembly of the receiver 1010, retainer 1012 and compression insert1014 is shown in FIGS. 71-75. First, the retainer 1012 is downloaded ina sideways manner into the receiver 1010 through the upper opening 1066with the outer surface 1130 facing the receiver channel seat 1068. Theretainer 1012 is then lowered between the arms 1062 and toward thereceiver base 1060 as shown in phantom in FIG. 71, the retainer beingturned or tilted to a position within the receiver base 1060 innercavity 1061 wherein the retainer bottom surface 1124 is manipulated to aposition facing the annular surface 1104 (also shown in phantom) andthen fully seated upon the inner base annular surface 1104 as shown insolid lines in FIG. 71. With reference to FIG. 72, the compressioninsert 1014 is then downloaded into the receiver 1010 through the upperopening 1066 with the crown collet extension bottom surfaces 1148 facingthe receiver arm top surfaces 1073 and the insert arms 1137 as well asthe insert collet extensions 1138 located between the opposed receiverarms 1062. The insert 1014 is then lowered toward the channel seat 1068until the insert 1014 arm upper surfaces 1144 are adjacent the run-outarea defined by the surfaces 1082 of the receiver below the guide andadvancement structure 1072. Thereafter, the insert 1014 is rotated in aclockwise or counter-clockwise manner about the receiver axis B untilthe upper arm surfaces 1144 are directly below the guide and advancementstructure 1072 as illustrated in FIG. 73 with the U-shaped channel 1141of the insert 1014 aligned with the U-shaped channel 1064 of thereceiver 1010. In some embodiments, the insert arms 1137 and colletextensions 1138 may need to be compressed slightly during rotation toclear inner surfaces of the receiver arms 1062. As shown in FIGS. 73-75,the outer cylindrical surfaces 1143 and 1152 of the insert 1014 arereceived within the cylindrical surfaces 1086 and 1090 of the receiver.With particular reference to FIGS. 74 and 75, the receiver thin walls ofthe sloping surface 1077 located about the arched through bore portion1075 are then crimped inwardly toward the axis B by inserting a tool(not shown) into the receiver apertures 1074, the tool pressing thesloped surface walls 1077 until the inner wall surfaces 1087 engage theinsert 1014 at the grooves 1160 and 1161 formed into the outercylindrical surface 1143 of each of the insert arms 1137. The crimpingof the opposed wall surfaces 1087 into the groves 1160 and 1161 keepsthe insert 1014 U-shaped channel 1141 substantially aligned with thereceiver U-shaped channel 1064, but allows for upward movement of theinsert 1014 along the receiver axis B during bottom loading of the shank1004 as shown in FIG. 77, for example. Thus, the crimping of thereceiver walls 1077 prohibits rotation of the insert 1104 about thereceiver axis B but allows for limited axial movement of the insert 1014with respect to the receiver 1010 along the axis B when some force isexerted to slide the crimped surface 1087 up or down along the grooves1160 and 1161. The insert 1014 arms 1137 are fully captured within thereceiver 1010 by the guide and advancement structure 1072 prohibitingmovement of the insert 1014 up and out through the receiver opening 1066as well as by the retainer 1012 and the receiver annular surface 1104located in the receiver 1010 base 1060 below the insert 1014.

In some embodiments of the invention, top or side surfaces of the insert1014 may include a resilient projection or projections for temporarilyfrictionally engaging with an inner surface of the receiver 1010 to holdthe insert 1014 in an upper portion of the receiver 1010 during some ofthe assembly steps, also providing a frictional but slidable fit betweenthe insert 1014 and the receiver 1010. In the illustrated embodiment,the insert 1014 is substantially freely slidable in the upper portion ofthe receiver 1010 in an axial direction, and sized an shaped so that theinsert 1014 is located above the cylindrical surface 1099 duringexpansion of the retainer 1012 about the shank head 1008, the surface1099 functioning as an expansion chamber or recess for the retainer1012.

At this time, the receiver, insert and retainer combination are readyfor shipping to an end user, with both the compression insert 1014 andthe retainer 1012 captured within the receiver 1010 in a manner thatsubstantially prevents movement or loss of such parts out of thereceiver 1010. The receiver 1010, compression insert 1014 and theretainer 1012 combination may now be assembled with the shank 1004either at the factory, by surgery staff prior to implantation, ordirectly upon an implanted shank 1004 as shown, for example, in FIG. 76,with the shank axis A and the receiver axis B either being alignedduring assembly as shown in FIG. 77 and most of the drawings figuresillustrating the assembly process, or the axes being at an angle withrespect to one another as shown in FIG. 76.

As illustrated in FIG. 76, the bone screw shank 1004 or an entireassembly 1001 made up of the assembled shank 1004, receiver 1010,retainer 1012 and compression insert 1014, is screwed into a bone, suchas the vertebra 1017, by rotation of the shank 1004 using a suitabledriving tool (not shown) that operably drives and rotates the shank body1006 by engagement thereof at the internal drive 10046. Specifically,the vertebra 1017 may be pre-drilled to minimize stressing the bone andhave a guide wire (not shown) inserted therein to provide a guide forthe placement and angle of the shank 1004 with respect to the vertebra.A further tap hole may be made using a tap with the guide wire as aguide. Then, the bone screw shank 1004 or the entire assembly 1001 isthreaded onto the guide wire utilizing the cannulation bore 1050 byfirst threading the wire into the opening at the bottom 1028 and thenout of the top opening at the drive feature 1046. The shank 1004 is thendriven into the vertebra using the wire as a placement guide. It isforeseen that the shank and other bone screw assembly parts, the rod1021 (also having a central lumen in some embodiments) and the closuretop 1018 (also with a central bore) can be inserted in a percutaneous orminimally invasive surgical manner, utilizing guide wires. When theshank 1004 is driven into the vertebra 1017 without the remainder of theassembly 1001, the shank 1004 may either be driven to a desired finallocation or may be driven to a location slightly above or proud toprovide for ease in assembly with the pre-assembled receiver,compression insert and retainer.

With reference to FIGS. 76 and 77, the pre-assembled receiver, insertand retainer are placed above the shank upper portion 1008 until theshank upper portion is received within the opening 1110. With particularreference to FIGS. 77 and 78, as the shank upper portion 1008 is movedinto the interior 1061 of the receiver base, the shank upper portion1008 presses the retainer 1012 upwardly into the recess partiallydefined by the cylindrical surface 1099 and partially by the annularsurface 1095. With particular reference to FIGS. 78 and 79, as theportion 1008 continues to move upwardly toward the channel 1064, the topsurface 1122 of the retainer 1012 abuts against the receiver annularsurface 1095, stopping upward movement of the retainer 1012 and forcingoutward movement of the retainer 1012 towards the cylindrical surface1099 defining the receiver expansion recess as the spherical surface1034 continues in an upward direction. With reference to FIGS. 80 and81, the retainer 1012 begins to contract about the spherical surface1034 as the center of the sphere of the head 1008 passes beyond thecenter of the retainer expansion recess defined by the surface 1099. Atthis time also, the spherical surface 1034 moves into engagement withthe insert 1014 collet panels 1155 at the panel inner planar surfaces1173, the panels 1155 initially expanding slightly outwardly to receivethe surface 1034. The panels 1155 press outwardly toward the surface1090 that provides enough clearance for the spherical surface 1034 toenter into full frictional engagement with the panel inner surfaces 1173as shown in FIG. 81. At this time, the insert 1014 and the surface 1034are in a fairly tight friction fit, the surface 1034 being pivotablewith respect to the insert 1014 with some force. Thus, a tight,non-floppy ball and socket joint is now created between the insert 1014and the shank upper portion 1008.

The shank 1004 and attached insert 1014 may then be manipulated furtherdownwardly into a desired position for receiving the rod 1021 or otherlongitudinal connecting member by either an upward pull on the receiver1010 or, in some cases, by driving the shank 1004 further into thevertebra 1017. Also, in some embodiments, when the receiver 1010 ispre-assembled with the shank 1004, the entire assembly 1001 may beimplanted at this time by inserting the driving tool (not shown) intothe receiver and the shank drive 1046 and rotating and driving the shank1004 into a desired location of the vertebra 1017. Also, at this time,the receiver 1010 and may be articulated to a desired angular positionwith respect to the shank 1004, such as that shown in FIG. 83, but priorto insertion of the rod or closure top, that will be held, but notlocked, by the frictional engagement between the retainer 1012 and theshank upper portion 1008.

With reference to FIGS. 82 and 83, the rod 1021 is eventually positionedin an open or percutaneous manner in cooperation with the at least twobone screw assemblies 1001. The closure structure 1018 is then insertedinto and advanced between the arms 1062 of each of the receivers 1010.The closure structure 1018 is rotated, using a tool engaged with theinner drive 1186 until a selected pressure is reached at which point therod 1021 engages the U-shaped seating surface 1142 of the compressioninsert 1014, pressing the insert stepped shank gripping surfaces 1170against the shank spherical surface 1034, the edges of the steppedsurfaces penetrating into the spherical surface 1034 and also pressingthe shank upper portion 1008 into locked frictional engagement with theretainer 1012. Specifically, as the closure structure 1018 rotates andmoves downwardly into the respective receiver 1010, the rim 1190 engagesand penetrates the rod surface 1022, the closure structure 1018 pressingdownwardly against and biasing the rod 1021 into compressive engagementwith the insert 1014 that urges the shank upper portion 1008 toward theretainer 1012 and into locking engagement therewith, the retainer 1012frictionally abutting the surface 1104 and expanding outwardly againstthe cylindrical surface 1101. For example, about 80 to about 120 inchpounds of torque on the closure top may be applied for fixing the bonescrew shank 1006 with respect to the receiver 1010.

With reference to FIGS. 84-89, an alternative lock-and-releasecompression insert 1014′ is illustrated for use with the shank 1004,receiver 1010, retainer 1012, closure top 1018 and rod 1021 previouslydescribed herein, the resulting assembly identified as an assembly 1001′in FIGS. 89 and 90, for example. The insert 1014′ is identical orsubstantially similar to the insert 1014 previously described herein,with the exception that the insert 1014′ is sized for a locking,frictional interference fit with the receiver 1010; specifically, alocking interference between the cylindrical inner surface 1090 of thereceiver 1010 and a lower portion of the outer cylindrical surfaces1143′ of the insert arms 1137′ as will be described in greater detailbelow. The illustrated insert 1014′ also differs from the insert 1014 inthat the insert 1014′ includes a pair of opposed through bores 1159′ forreceiving tooling as will be described in greater detail below.

Thus, with reference to FIGS. 84-86, the locking insert 1014 includes abody 1136′, a pair of opposed arms 1137′, a pair of crown colletextensions 1138′, a through bore 1140′, a u-shaped saddle surface 1141′with a seat 1142′, arm outer surfaces 1143′, arm top surfaces 1144′,collet extension bottom surfaces 1148′, arms rim or ledge surfaces1150′, annular lower body surfaces 1151′, lower outer cylindricalsurfaces 1152′, slots 1154′, panels 1155′ formed by the slots, notches1156′ having an upper sloping surface 1157′ and a lower planar surface1158′, a pair of grooves 1160′ and 1161′, having respective bottomsurfaces 1162′ and 1163′, inner planar opposed surfaces 1165′, innercylindrical surfaces 1166′, an inner spherical profile 1168′ with agripping surface portion 1170′, curved inner surfaces 1172′ and colletplanar inner gripping friction fit surfaces 1173′ that are the same orsubstantially similar in form and function to the respective body 1136,pair of opposed arms 1137, pair of crown collet extensions 1138, throughbore 1140, u-shaped saddle surface 1141 with seat 1142, arm outersurfaces 1143, arm top surfaces 1144, collet extension bottom surfaces1148, arms rim or ledge surfaces 1150, annular lower body surfaces 1151,lower outer cylindrical surfaces 1152, slots 1154, panels 1155 formed bythe slots, notches 1156 having upper sloping surfaces 1157 and a lowerplanar surface 1158, pair of grooves 1160 and 1161 having respectivebottom surfaces 1162 and 1163, inner planar opposed surfaces 1615, innercylindrical surfaces 1166, inner spherical profile 1168 with a grippingsurface portion 1170, curved inner surfaces 1172 and planar friction fitgripping surfaces 1173 previously described herein with respect to theinsert 1014.

The insert 1014′ outer cylindrical surfaces 1143′ that are located belowthe tooling notches 1156′ and at or near the ledge or rim 1150′ aresized and shaped for a locking interference fit with the receiver 1010at the cylindrical surface 1090 that partially defines the inner cavity1061. In other words, a width or diameter measured between arm surfaces1143′ at or directly above the rim 1150′ is sized large enough torequire that the insert 1014′ must be forced into the space defined bythe cylindrical surface 1090 starting at the edge defined by thereceiver surface 1088 and the surface 1090 by a tool or tools or by theclosure top 1018 forcing the rod 1021 downwardly against the insert1014′ with sufficient force to interferingly lock the insert 1014′ intothe receiver 1010 at the cylindrical surface 1090.

With reference to FIGS. 87-90, the insert 1014′ is assembled with thereceiver 1010, retainer 1012, shank 1004, rod 1021 and closure top 1018,in a manner the same as previously described above with respect to theassembly 1001, resulting in an assembly 1001′, with the exception thatthe insert 1014′ must be forced downwardly into a locking interferencefit with the receiver 1010 when the shank 1004 is locked in place, ascompared to the easily sliding relationship between the insert 1014 andthe receiver 1010. In particular, prior to assembly with the rod 1021and the closure top 1018, the compression insert 1014′ outer cylindricalsurfaces 1152′ are slidingly received by receiver cylindrical surface1090, but the surfaces 1143′ are not. The insert 1014′ is thusprohibited from moving any further downwardly at the receiver surface1088 unless forced downwardly by a locking tool or by the closure toppressing downwardly on the rod that in turn presses downwardly on theinsert 1014′ as shown in FIGS. 89 and 90. With further reference to FIG.89, at this time, the receiver 1010 may be articulated to a desiredangular position with respect to the shank 1004, such as that shown inFIG. 96, for example, that will be held, but not locked, by thefrictional engagement between the retainer 1012 collet panels and theshank upper portion 1008.

The rod 1021 is eventually positioned in an open or percutaneous mannerin cooperation with the at least two bone screw assemblies 1001′. Theclosure structure 1018 is then inserted into and advanced between thearms 1062 of each of the receivers 1010. The closure structure 1018 isrotated, using a tool engaged with the inner drive 1186 until a selectedpressure is reached at which point the rod 1021 engages the U-shapedseating surface 1142′ of the compression insert 1014′, pressing theinsert stepped shank gripping surfaces 1170′ against and into the shankspherical surface 1034, the edges of the stepped surfaces 1170′penetrating into the spherical surface 1034, pressing the shank upperportion 1008 into locked frictional engagement with the retainer 1012.Specifically, as the closure structure 18 rotates and moves downwardlyinto the respective receiver 1010, the rim 1190 engages and penetratesthe rod surface 1022, the closure structure 1018 pressing downwardlyagainst and biasing the rod 1021 into compressive engagement with theinsert 1014′ that urges the shank upper portion 1008 toward the retainer1012 and into locking engagement therewith, the retainer 1012frictionally abutting the surface 1104 and expanding outwardly againstthe cylindrical surface 1101. For example, about 80 to about 120 inchpounds of torque on the closure top may be applied for fixing the bonescrew shank 1006 with respect to the receiver 1010. Tightening thehelical flange form to approximately 100 inch pounds can create around900 to 1000 pounds of force and it has been found that the interferencefit created between the cylindrical surfaces 1143′ of the insert 1014′and the cylindrical surface 1090 of the receiver can be overcome atbetween about 500 to 700 inch pounds depending on manufacturingtolerance issues between the parts. So, as the closure structure 1018and the rod 1021 press the insert 1014′ downwardly toward the base ofthe receiver 1010, the insert surfaces 1143′ are forced into thereceiver at the edge defined by the receiver annular surface 1088 andthe cylindrical surface 1090, thus forcing and fixing the insert 1014into frictional interference engagement with the receiver at and alongthe surface 1090, while not substantially affecting the locking of thepolyaxial mechanism itself.

With reference to FIG. 91, at this time, the closure top 1018 may beloosened or removed and/or the rod 1021 may be adjusted and/or removedand the frictional engagement between the insert 1014′ and the receiver1010 at the insert surfaces 1143′ will remain locked in place,advantageously maintaining a locked angular position of the shank 1004with respect to the receiver 1010.

With further reference to FIGS. 91 and 92, at this time, another rod,such as the deformable rod 1221 and cooperating alternative closure top1218 may be loaded onto the already locked-up assembly to result in analternative assembly 1201′. As mentioned above, the closure drive 1286may advantageously be made smaller than the drive of the closure 1018,such that the deformable rod 1221 is not unduly pressed or deformedduring assembly since the polyaxial mechanism is already locked.

With reference to FIGS. 93-95, a two-piece tool, generally 1600, isillustrated for releasing the insert 1014′ from the receiver 1010. Thetool 1600 includes an inner flexible tube-like structure with opposedinwardly facing prongs 1612 located on either side of a through-channel1616. The channel 1616 may terminate at a location spaced from theprongs 1612 or may extend further upwardly through the tool, resultingin a two-piece tool 1610. The tool 1600 includes an outer, more rigidtubular member 1620 having a smaller through channel 1622. The member1620 slidingly fits over the tube 1610 after the flexible member 1610prongs 1612 are flexed outwardly and then fitted over the receiver 1010and then within through bores of the opposed apertures 1074 of thereceiver 1010 and aligned opposed bores 1159′ located on arms of theinsert 1014′. In FIG. 93, the tool 1600 is shown during the process ofunlocking the insert 1014′ from the receiver 1010 with the outer member1620 surrounding the inner member 1610 and holding the prongs 1612within the receiver 1010 and insert 1014′ apertures while the tool 1600is pulled upwardly away from the shank 1004. It is foreseen that thetool 1600 may further include structure for pressing down upon thereceiver 1010 while the prongs and tubular member are pulled upwardly,such structure may be located within the tool 1600 and press down uponthe top surfaces 1073 of the receiver arms, for example.

Alternatively, another manipulation tool (not shown) may be used that isinserted into the receiver at the opening 1066 and into the insertchannel formed by the saddle 1141′, with prongs or extensions thereofextending outwardly into the insert through bores 1159′; a piston-likeportion of the tool thereafter pushing directly on the shank upperportion 1008, thereby pulling the insert 1014′ away from the receiversurface 1090 and thus releasing the polyaxial mechanism. At such time,the shank 1004 may be articulated with respect to the receiver 1010, andthe desired friction fit returns between the retainer 1012 and the shanksurface 1034, so that an adjustable, but non-floppy relationship stillexists between the shank 1004 and the receiver 1010. If furtherdisassembly if the assembly is desired, such is accomplished in reverseorder to the procedure described previously herein for the assembly1001.

With reference to FIGS. 96-98, another manipulation tool, generally1700, is illustrated for independently locking the insert 1014′, or, insome embodiments, temporarily locking the non-locking insert 1014, tothe receiver 1010. The tool 1700 includes a pair of opposed arms 1712,each having an engagement extension 1716 positioned at an angle withrespect to the respective arm 1712 such that when the tool is moveddownwardly toward the receiver, one or more inner surfaces 1718 of theengagement extension 1716 slide along the surfaces 1077 of the receiverand along 1157′ of the insert 1014′ to engage the insert 1014′, with asurface 1720 pressing downwardly on the insert surfaces 1158′, pushingthe cylindrical arm surfaces 1143′ into an interference locking fitwithin the receiver cylindrical surface 1090. As shown in FIG. 98, whenthe insert 1014′ is locked against the receiver 1010, the tool bottomsurfaces 1720 do not bottom out on the receiver surfaces 7105′, butremained spaced therefrom. In the illustrated embodiment, the surface1718 is slightly rounded and each arm extension 1716 further includes aplanar lower surface 1722 that creates an edge with the bottom surface1720 for insertion and gripping of the insert 1014′ at the juncture ofthe surface 1157′ and the surface 1158′. The tool 1700 may include avariety of holding and pushing/pulling mechanisms, such as a pistol griptool, that may include a ratchet feature, a hinged tool, or, a rotatablythreaded device, for example.

It is to be understood that while certain forms of the present inventionhave been illustrated and described herein, it is not to be limited tothe specific forms or arrangement of parts described and shown.

What is claimed is:
 1. A method of assembling a receiver assembly of abone anchor assembly for securing a rod to a bone, the methodcomprising: placing an insert into a receiver having a rod-receivingchannel, the insert having a unitary-construction including a saddlesurface, first engagement features adjacent the saddle surface, adownward-facing collet opposite the saddle surface, and rotationblocking extensions oriented in a direction of the receiver channel, therotation blocking extensions blocking rotation between the insert andreceiver when the insert is in the receiver, the rotation blockingextensions extending under a most bottom surface of the rod when the rodis received in the rod-receiving channel and against the saddle surface;and causing the insert to engage with the receiver in an upperengagement position that is above a lower engagement position, thereceiver including an upper opening, a bottom opening opposite the upperopening, and a base cavity extending upward from the bottom opening, therod-receiving channel extending downward from the upper opening and incommunication with the base cavity to form a through space of thereceiver extending between the upper opening and bottom opening, thereceiver further including a discontinuous helically wound guide andadvancement structure extending along an upper portion of therod-receiving channel, upper engagement features in the through spaceand below the discontinuous helically wound guide and advancementstructure, and lower engagement features in the through space, at leastsome of the lower engagement features being below the upper engagementfeatures, wherein the upper engagement position includes at least someof the first engagement features abutting the upper engagement featuresas the saddle surface faces upward within the receiver and the colletfaces downward within the receiver, and wherein the lower engagementposition includes at least some of the first features abutting the lowerengagement features as the saddle surface faces upward within thereceiver and the collet faces downward within the receiver.
 2. Themethod of claim 1, further comprising shipping the receiver assemblywith the insert engaged with the receiver in the upper engagementposition.
 3. The method of claim 2, wherein, when the insert is engagedwith the receiver in the upper engagement position, such engagementbetween the insert and receiver inhibits the insert from moving backupwardly within the receiver.
 4. The method of claim 1, furthercomprising, subsequent to shipping the receiver assembly with the insertengaged with the receiver in the upper engagement position, causing theinsert is to be moved into engagement with the receiver in the lowerengagement position.
 5. The method of claim 4, wherein, when the insertis engaged with the receiver in the upper engagement position or thelower engagement position, at least one of such engagements between theinsert and receiver inhibits the insert from moving back upwardly withinthe receiver.
 6. The method of claim 1, further comprising, subsequentto shipping the receiver assembly with the insert engaged with thereceiver in the upper engagement position, causing a head of a boneattachment structure to be uploaded into the collet such that the boneattachment structure extends through the bottom opening and a body ofthe bone attachment structure can articulate relative to the receiver ina non-floppy relationship.
 7. The method of claim 6, wherein, when theinsert is engaged with the receiver in the upper engagement position,such engagement between the insert and receiver inhibits the insert frommoving back upwardly within the receiver.
 8. The method of claim 1,wherein, when the insert is engaged with the receiver in the upperengagement position, the insert is inhibited from moving back upwardlywithin the receiver.
 9. The method of claim 1, wherein, when the insertis engaged with the receiver in the lower engagement position, theinsert is inhibited from moving back upwardly within the receiver. 10.The method of claim 1, wherein, when the insert is engaged with thereceiver in the lower engagement position, the insert is inhibited frommoving back upwardly within the receiver by the at least some of thefirst features snapping into engagement with the lower engagementfeatures of the receiver.
 11. The method of claim 1, wherein the firstengagement features of the insert include upward-facing engagementfeatures and the lower engagement features of the receiver includedownward-facing engagement features, and wherein, when the insert isengaged with the receiver in the lower engagement position, a snap-fitengagement is formed by the at least some of the upward-facingengagement features of the first engagement features of the insertupwardly abutting the downward-facing engagement features of the lowerengagement features of the receiver.
 12. The method of claim 1, wherein,when the insert is engaged with the receiver in the lower engagementposition, the insert can be moved back upwardly within the receiver by atool.
 13. The method of claim 1, wherein the at least some of the firstengagement features of the insert include outward-facing surfaces andupward-facing surfaces, the outward-facing surfaces radially outwardlyabutting against at least some of the upper engagement features of thereceiver when the insert is engaged with the receiver in the upperengagement position, and the upward-facing surfaces upwardly abuttingagainst at least some of the lower engagement features of the receiveronce the insert is engaged with the receiver in the lower engagementposition.
 14. The method of claim 1, wherein the at least some of thefirst engagement features of the insert include outward-facing surfacesradially outwardly abutting against at least some of the upperengagement features of the receiver when the insert is engaged with thereceiver in the upper engagement position.
 15. The method of claim 1,wherein the at least some of the first engagement features of the insertinclude upward-facing surfaces, the upward-facing surfaces upwardlyabutting against at least some of the lower engagement features of thereceiver once the insert is engaged with the receiver in the lowerengagement position.
 16. The method of claim 1, wherein, when the insertis engaged with the receiver in the upper engagement position, a head ofa bone attachment structure can be uploaded into the collet such thatthe bone attachment structure extends through the bottom opening and abody of a bone attachment structure can articulate relative to thereceiver in a non-floppy relationship.
 17. The method of claim 16,wherein the base cavity allows for expansion of the collet as the headis uploaded into the collet.
 18. The method of claim 17, wherein thecollet includes downwardly extending collet sections separated bydownwardly extending slots, the collet sections defining a discontinuousinner spherical surface.
 19. The method of claim 18, wherein, when thebone attachment structure extends through the bottom opening and thebody can articulate relative to the receiver in the non-floppyrelationship, the head is at least partially enclosed by thediscontinuous inner spherical surface defined by the collet sections.20. The method of claim 19, wherein, when the bone attachment structureextends through the bottom opening and the body can articulate relativeto the receiver in the non-floppy relationship, the collet is located inthe base cavity of the receiver.
 21. The method of claim 1, furthercomprising causing the insert is to be moved into engagement with thereceiver in the lower engagement position.
 22. The method of claim 21,wherein, when the insert is engaged with the receiver in the upperengagement position or the lower engagement position, at least one ofsuch engagements between the insert and receiver inhibits the insertfrom moving back upwardly within the receiver.
 23. The method of claim1, further comprising causing a head of a bone attachment structure tobe uploaded into the collet such that the bone attachment structureextends through the bottom opening and a body of the bone attachmentstructure can articulate relative to the receiver in a non-floppyrelationship.
 24. The method of claim 23, wherein, when the insert isengaged with the receiver in the upper engagement position, suchengagement between the insert and receiver inhibits the insert frommoving back upwardly within the receiver.